[google_fonts] Make a map keyed on FontWeight non-const (#10058)

A proposed engine PR will allow construction of arbitrary FontWeight instances and thus needs to overload the FontWeight equality operator (see flutter/flutter#175771)

With that change it will no longer be possible to use FontWeight as the key in a const map.

Author: jason-simmons

packages/google_fonts/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 6.3.2
+
+- Makes a map keyed on FontWeight non-const for compatibility with proposed changes to the engine's implementation of FontWeight.
+
 ## 6.3.1
 
 - Transfers the package source from

packages/google_fonts/lib/src/google_fonts_variant.dart

@@ -171,7 +171,7 @@ const String _italic = 'italic';
 
 /// Mapping from font weight types to the 'weight' part of the Google Fonts API
 /// specific filename.
-const Map<FontWeight, String> _fontWeightToFilenameWeightParts =
+final Map<FontWeight, String> _fontWeightToFilenameWeightParts =
     <FontWeight, String>{
       FontWeight.w100: 'Thin',
       FontWeight.w200: 'ExtraLight',

packages/google_fonts/pubspec.yaml

@@ -2,7 +2,7 @@ name: google_fonts
 description: A Flutter package to use fonts from fonts.google.com. Supports HTTP fetching, caching, and asset bundling.
 repository: https://github.com/flutter/packages/tree/main/packages/google_fonts
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+google_fonts%22
-version: 6.3.1
+version: 6.3.2
 
 environment:
   sdk: ^3.7.0