Format all gitignore files with shfmt

Flutter.gitignore

@@ -7,8 +7,6 @@
 .buildlog/
 .history
 
-
-
 # Flutter repo-specific
 /bin/cache/
 /bin/internal/bootstrap.bat
@@ -116,4 +114,4 @@ app.*.symbols
 !**/ios/**/default.pbxuser
 !**/ios/**/default.perspectivev3
 !/packages/flutter_tools/test/data/dart_dependencies_test/**/.packages
-!/dev/ci/**/Gemfile.lock
+!/dev/ci/**/Gemfile.lock