.github: Bump tibdex/github-app-token from 1.8.0 to 2.1.0

Bumps [tibdex/github-app-token](https://github.com/tibdex/github-app-token) from 1.8.0 to 2.1.0.
- [Release notes](https://github.com/tibdex/github-app-token/releases)
- [Commits](tibdex/github-app-token@b625283...3beb63f)

---
updated-dependencies:
- dependency-name: tibdex/github-app-token
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/go-licenses.yml

@@ -42,7 +42,7 @@ jobs:
           go-licenses report tailscale.com/cmd/tailscale tailscale.com/cmd/tailscaled > licenses/tailscale.md --template .github/licenses.tmpl
 
       - name: Get access token
-        uses: tibdex/github-app-token@b62528385c34dbc9f38e5f4225ac829252d1ea92 # v1.8.0
+        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2.1.0
         id: generate-token
         with:
           app_id: ${{ secrets.LICENSING_APP_ID }}

.github/workflows/update-flake.yml

@@ -27,7 +27,7 @@ jobs:
         run: ./update-flake.sh
 
       - name: Get access token
-        uses: tibdex/github-app-token@b62528385c34dbc9f38e5f4225ac829252d1ea92 # v1.8.0
+        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2.1.0
         id: generate-token
         with:
           app_id: ${{ secrets.LICENSING_APP_ID }}

.github/workflows/update-webclient-prebuilt.yml

@@ -23,7 +23,7 @@ jobs:
           ./tool/go mod tidy
 
       - name: Get access token
-        uses: tibdex/github-app-token@b62528385c34dbc9f38e5f4225ac829252d1ea92 # v1.8.0
+        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2.1.0
         id: generate-token
         with:
           # TODO(will): this should use the code updater app rather than licensing.