Adopt Xcode 12 for podspec lints (#3653)

script/tool/lib/src/lint_podspecs_command.dart

@@ -122,6 +122,7 @@ class LintPodspecsCommand extends PluginCommand {
       'lib',
       'lint',
       podspecPath,
+      '--configuration=Debug', // Release targets unsupported arm64 simulators. Use Debug to only build against targeted x86_64 simulator devices.
       if (allowWarnings) '--allow-warnings',
       if (libraryLint) '--use-libraries'
     ];