Update GitHub Actions workflows. (#976)

This PR was automatically generated by the
update-workflows-ecosystem-providers workflow in the pulumi/ci-mgmt
repo, from commit bebe923d5312b1d1e63075152151c7d964c49db5.

.github/workflows/upgrade-provider.yml

@@ -78,7 +78,7 @@ jobs:
           username: pulumi-bot
           automerge: true
           target-version: ${{ steps.target_version.outputs.version }}
-          allow-missing-docs: false
+          allow-missing-docs: true
       - name: Comment on upgrade issue if automated PR failed
         if: steps.upgrade_provider.outcome == 'failure'
         shell: bash