Update CI Toolkit plugin to workaround a CocoaPods issue

This will unblock us from testing and release pod from CI.

See:

- wordpress-mobile/WordPressAuthenticator-iOS@6bb3c53
- Automattic/a8c-ci-toolkit-buildkite-plugin#78

.buildkite/pipeline.yml

@@ -1,7 +1,7 @@
 # Nodes with values to reuse in the pipeline.
 common_params:
   plugins: &common_plugins
-    - automattic/a8c-ci-toolkit#2.17.0
+    - automattic/a8c-ci-toolkit#3.0.1
   # Common environment values to use with the `env` key.
   env: &common_env
     IMAGE_ID: xcode-15.0.1
@@ -44,12 +44,7 @@ steps:
   - label: "🔬 Validating Podspec"
     key: "validate"
     command: |
-      # validate_podspec
-      echo '+++ ⚠️ validate_podspec was bypassed ⚠️'
-      # post a message in the logs
-      cat .buildkite/validate_podspec_annotation.md
-      # and also as an annotation
-      cat .buildkite/validate_podspec_annotation.md | buildkite-agent annotate --style 'warning'
+      validate_podspec --patch-cocoapods
     env: *common_env
     plugins: *common_plugins
     artifact_paths: ".build/logs/*.log"

.buildkite/publish-pod.sh

@@ -8,7 +8,7 @@ echo "--- :rubygems: Setting up Gems"
 install_gems
 
 echo "--- :cocoapods: Publishing Pod to CocoaPods CDN"
-publish_pod $PODSPEC_PATH
+publish_pod --patch-cocoapods $PODSPEC_PATH
 
 echo "--- :slack: Notifying Slack"
-slack_notify_pod_published $PODSPEC_PATH $SLACK_WEBHOOK
+slack_notify_pod_published $PODSPEC_PATH "$SLACK_WEBHOOK"