flutter pub upgrade (#241)

gallery/gallery/pubspec.lock

@@ -1,13 +1,20 @@
 # Generated by pub
 # See https://dart.dev/tools/pub/glossary#lockfile
 packages:
+  _fe_analyzer_shared:
+    dependency: transitive
+    description:
+      name: _fe_analyzer_shared
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "1.0.3"
   analyzer:
     dependency: transitive
     description:
       name: analyzer
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.38.5"
+    version: "0.39.4"
   archive:
     dependency: transitive
     description:
@@ -149,13 +156,6 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
-  front_end:
-    dependency: transitive
-    description:
-      name: front_end
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.1.27"
   glob:
     dependency: transitive
     description:
@@ -197,7 +197,7 @@ packages:
       name: intl_translation
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.17.7"
+    version: "0.17.9"
   js:
     dependency: transitive
     description:
@@ -205,13 +205,6 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "0.6.1+1"
-  kernel:
-    dependency: transitive
-    description:
-      name: kernel
-      url: "https://pub.dartlang.org"
-    source: hosted
-    version: "0.3.27"
   matcher:
     dependency: transitive
     description:
@@ -412,7 +405,7 @@ packages:
       name: url_launcher_platform_interface
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.0.4"
+    version: "1.0.5"
   url_launcher_web:
     dependency: transitive
     description:
@@ -449,5 +442,5 @@ packages:
     source: hosted
     version: "2.2.0"
 sdks:
-  dart: ">=2.5.0 <3.0.0"
+  dart: ">=2.6.0 <3.0.0"
   flutter: ">=1.12.13+hotfix.4 <2.0.0"