[ci] Exclude packages using deprecated APIs from the pod linter check (#9746)

Xcode 26 is showing deprecation usage as warnings: flutter/flutter#170437. These warnings are causing `podspec-check` to fail as these warnings are being treated as errors.
To unblock testing Xcode 26 in CI, exclude the existing `exclude_xcode_deprecation` packages from the podspec check command.

Currently used here:
https://github.com/flutter/packages/blob/83ae18a4faf6cbd18138d6fe7a20859a28b84166/.ci/targets/ios_platform_tests.yaml#L21
https://github.com/flutter/packages/blob/83ae18a4faf6cbd18138d6fe7a20859a28b84166/.ci/targets/macos_platform_tests.yaml#L18

This isn't a perfect solution, as the podspec check will find more issues than just deprecation warnings (Swift 6 warnings, [for example](flutter/flutter#170439)), and this will prevent any warnings being discovered for these packages. However, I believe it's a better solution than #9428 (not treating warnings as errors for any package) because NEW regression warnings in all other packages can be caught in presubmit.

Closes #9428

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Author: jmagman

.ci/targets/macos_repo_checks.yaml

@@ -13,5 +13,5 @@ tasks:
     always: true
   - name: validate iOS and macOS podspecs
     script: .ci/scripts/tool_runner.sh
-    args: ["podspec-check"]
+    args: ["podspec-check", "--exclude=script/configs/exclude_xcode_deprecation.yaml"]
     always: true