Allow to skip signature verification (#741)

## Changes

- Allow skipping signature verification for webhooks

## Motivation

The signature returned with webhooks is calculated using a single
channel secret. If the bot owner changes their channel secret, the
signature for webhooks starts being calculated using the new channel
secret. To avoid signature verification failures, the bot owner must
update the channel secret on their server, which is used for signature
verification. However, if there is a timing mismatch in the update—and
such a mismatch is almost unavoidable—verification will fail during that
period.

In such cases, having an option to skip signature verification for
webhooks would be a convenient way to avoid these issues.

Author: habara-k

.github/workflows/generate-code.yml

@@ -53,7 +53,7 @@ jobs:
           bash tools/gen-oas-client.sh
       - name: Update document
         run: |
-          wget https://github.com/phpDocumentor/phpDocumentor/releases/download/v3.3.1/phpDocumentor.phar
+          wget https://github.com/phpDocumentor/phpDocumentor/releases/download/v3.8.1/phpDocumentor.phar
           php phpDocumentor.phar run -d src -t docs
       - run: |
           diff_files=$(git --no-pager diff --name-only)
@@ -64,6 +64,21 @@ jobs:
 
           echo "DIFF_IS_EMPTY=$([[ -z "$diff_excluding_submodule" ]] && echo 'true' || echo 'false')" >> $GITHUB_ENV
           echo "CURRENT_DATETIME=$(date +'%Y%m%d%H%M%S')" >> $GITHUB_ENV
+
+      # Save full diff to file and upload artifact
+      - name: Save full diff to file
+        if: env.DIFF_IS_EMPTY != 'true'
+        run: |
+          git --no-pager diff HEAD > diff.patch
+          echo "Full diff saved to diff.patch"
+
+      - name: Upload diff artifact
+        if: env.DIFF_IS_EMPTY != 'true'
+        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2
+        with:
+          name: codegen-diff
+          path: diff.patch
+
       ## Run if diff exists and pull request or merge queue, and make CI status failure (but allow renovate bot)
       ## 29139614 is renovate bot's actor id
       - if: >-