Move to separate Cirrus task

Author: jmagman

.cirrus.yml

@@ -122,4 +122,15 @@ task:
         - flutter channel $CHANNEL
         - ./script/incremental_build.sh build-examples --ipa
         - ./script/incremental_build.sh drive-examples
+    - name: lint-podspecs
+      env:
+        PATH: $PATH:/usr/local/bin
+        matrix:
+          CHANNEL: "master"
+          CHANNEL: "stable"
+      build_script:
+        # TODO(jackson): Allow web plugins once supported on stable
+        # https://github.com/flutter/flutter/issues/42864
+        - if [[ "$CHANNEL" -eq "stable" ]]; then find . | grep _web$ | xargs rm -rf; fi
+        - flutter channel $CHANNEL
         - ./script/incremental_build.sh podspecs --skip url_launcher_web --skip google_sign_in_web --skip e2e_macos --skip video_player_web --no-analyze camera