fix: update pr-comment workflow to v0.0.37 with git revision syntax

Switch from raw GitHub URL to git ref syntax (origin/base:file and HEAD:file),
add git fetch step, bump action to v0.0.37, and use secrets.OASDIFF_TOKEN
per the current docs at https://www.oasdiff.com/docs/github-action

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: reuvenharrison

.github/workflows/pr-comment.yml

@@ -15,9 +15,12 @@ jobs:
     - name: Check out code
       uses: actions/checkout@v4
 
+    - name: Fetch base branch
+      run: git fetch --depth=1 origin ${{ github.base_ref }}
+
     - name: Post oasdiff PR comment
-      uses: oasdiff/oasdiff-action/pr-comment@v0.0.34
+      uses: oasdiff/oasdiff-action/pr-comment@v0.0.37
       with:
-        base: https://raw.githubusercontent.com/${{ github.repository }}/${{ github.event.pull_request.base.sha }}/multi-file/openapi.yaml
-        revision: multi-file/openapi.yaml
-        oasdiff-token: 0634345d-02fb-43df-b56a-68fc22253621
+        base: 'origin/${{ github.base_ref }}:multi-file/openapi.yaml'
+        revision: 'HEAD:multi-file/openapi.yaml'
+        oasdiff-token: ${{ secrets.OASDIFF_TOKEN }}