Fix sample index deployment action (#862)

* Update sample index dependencies

* Update to tuneup 0.3.8, update dependencies

* Upgrade to null safety, lock sass version

* fix analyzer warnings

* Fix unit tests

* Fix issues from upgrading to null safety

web/samples_index/lib/src/samples.yaml

@@ -83,6 +83,7 @@ samples:
       - scoped_model
     tags: ['intermediate', 'sample', 'gallery', 'material', 'design', 'vignettes']
     platforms: ['web', 'ios', 'android']
+    links: []
     type: demo
 
   - name: Add to App
@@ -105,6 +106,7 @@ samples:
       - provider
     tags: ['advanced', 'sample', 'add-to-app', 'android', 'ios', 'native', 'embedding']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: Animations
@@ -133,6 +135,7 @@ samples:
       - flutter/material
     tags: ['intermediate', 'sample', 'animation']
     platforms: ['ios', 'android', 'web']
+    links: []
     type: sample
     web: web/animations
 
@@ -157,6 +160,7 @@ samples:
       - google_maps_webservice
     tags: ['intermediate', 'sample', 'firebase', 'maps']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: Isolate Example
@@ -181,6 +185,7 @@ samples:
       - dart:math
     tags: ['intermediate', 'sample', 'isolates', 'concurrency']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: jsonexample
@@ -209,6 +214,7 @@ samples:
       - built_value_generator
     tags: ['beginner', 'sample']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: Place Tracker
@@ -235,6 +241,7 @@ samples:
       - google_maps_flutter
     tags: ['intermediate', 'sample', 'json', 'serialization']
     platforms: ['android']
+    links: []
     type: sample
 
   - name: Platform Design
@@ -266,6 +273,7 @@ samples:
       - flutter/cupertino
     tags: ['advanced', 'sample', 'ios']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: Platform View Swift
@@ -287,6 +295,7 @@ samples:
       - flutter/services
     tags: ['advanced', 'sample', 'ios']
     platforms: ['ios']
+    links: []
     type: sample
 
   - name: Infinite List
@@ -311,6 +320,7 @@ samples:
       - meta
     tags: ['sample', 'material', 'design', 'android', 'ios']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: IOS App Clip
@@ -331,6 +341,7 @@ samples:
       - device_info
     tags: ['sample', 'Device Info', 'ios']
     platforms: ['ios']
+    links: []
     type: sample
 
   - name: Testing App
@@ -353,6 +364,7 @@ samples:
       - provider
     tags: ['sample', 'material', 'android', 'ios']
     platforms: ['ios', 'android']
+    links: []
     type: sample
 
   - name: Provider Shopper
@@ -376,6 +388,7 @@ samples:
       - provider
     tags: ['intermediate', 'sample', 'provider']
     platforms: ['ios', 'android', 'web']
+    links: []
     type: sample
     web: web/provider_shopper
 
@@ -402,6 +415,7 @@ samples:
       - firebase
     tags: ['intermediate', 'sample', 'firebase']
     platforms: ['ios', 'android', 'web']
+    links: []
     type: sample
     web: web/web_dashboard
 
@@ -423,6 +437,7 @@ samples:
     packages: []
     tags: ['intermediate', 'sample', 'forms']
     platforms: ['ios', 'android', 'web']
+    links: []
     type: sample
     web: web/form_app
 ###################
@@ -433,6 +448,7 @@ samples:
     author: Flutter
     screenshots:
       - url: images/charts1.png
+        alt: Charts screenshot
     source: https://github.com/google/charts
     description: >
       A general-purpose charting library.
@@ -440,6 +456,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['ios', 'android', 'web']
+    links: []
     tags: ['demo', 'charts']
     web: web/charts
     type: demo
@@ -456,6 +473,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['web']
+    links: []
     tags: ['demo', 'flutter create']
     web: web/filipino_cuisine
     type: demo
@@ -472,6 +490,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['web']
+    links: []
     tags: ['demo', 'data', 'visualization']
     web: web/github_dataviz
     type: demo
@@ -488,6 +507,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['web']
+    links: []
     tags: ['demo', 'animation']
     web: web/particle_background
     type: demo
@@ -504,6 +524,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['web']
+    links: []
     tags: ['demo', 'game']
     web: web/slide_puzzle
     type: demo
@@ -520,6 +541,7 @@ samples:
     widgets: []
     packages: []
     platforms: ['web']
+    links: []
     tags: ['demo', 'animation']
     web: https://z.flutter.gallery/#/dice
     type: demo