build(deps): bump mxschmitt/action-tmate from 3.20 to 3.21

Bumps [mxschmitt/action-tmate](https://github.com/mxschmitt/action-tmate) from 3.20 to 3.21.
- [Release notes](https://github.com/mxschmitt/action-tmate/releases)
- [Changelog](https://github.com/mxschmitt/action-tmate/blob/master/RELEASE.md)
- [Commits](mxschmitt/action-tmate@c6f0481...c606f86)

---
updated-dependencies:
- dependency-name: mxschmitt/action-tmate
  dependency-version: '3.21'
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/govmomi-go-tests.yaml

@@ -52,4 +52,4 @@ jobs:
 
       - name: Debug on Failure
         if: ${{ failure() }}
-        uses: mxschmitt/action-tmate@c6f0481d0648e44da05d377e11809430c8685366 # v3.20
+        uses: mxschmitt/action-tmate@c606f8612a802e46b3742322514c09fbc8c4afee # v3.21

.github/workflows/govmomi-govc-tests.yaml

@@ -56,7 +56,7 @@ jobs:
 
       - name: Debug on Failure
         if: ${{ failure() }}
-        uses: mxschmitt/action-tmate@c6f0481d0648e44da05d377e11809430c8685366 # v3.20
+        uses: mxschmitt/action-tmate@c606f8612a802e46b3742322514c09fbc8c4afee # v3.21
 
   govc-docs:
     name: Verify Updated Docs