chore: update snapshot workflow (#412)

Signed-off-by: Keith Zantow <kzantow@gmail.com>

.github/workflows/update-snapshots.yml

@@ -12,6 +12,22 @@ jobs:
         ports:
           - 5000:5000
     steps:
+      - uses: actions/github-script@v3
+        id: get-pr
+        with:
+          script: |
+            const request = {
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: context.issue.number
+            }
+            core.info(`Getting PR #${request.pull_number} from ${request.owner}/${request.repo}`)
+            try {
+              const result = await github.pulls.get(request)
+              return result.data
+            } catch (err) {
+              core.setFailed(`Request failed with error ${err}`)
+            }
       - name: Generate token
         uses: tibdex/github-app-token@v1
         id: generate-token
@@ -27,6 +43,8 @@ jobs:
         uses: actions/checkout@v3
         with:
           token: ${{ steps.generate-token.outputs.token }}
+          repository: ${{ fromJSON(steps.get-pr.outputs.result).head.repo.full_name }}
+          ref: ${{ fromJSON(steps.get-pr.outputs.result).head.ref }}
       - name: Build images
         run: |
           for distro in alpine centos debian; do