infra: Convert from old autolabeler GitHub App to new GitHub actions version.

The old autolabeler GitHub App is no longer supported and broken. The
new GitHub actions autolabeler is maintained by GitHub.

Signed-off-by: Tim 'mithro' Ansell <me@mith.ro>

.github/labeler.yml

diff --git a/.github/autolabeler.yml b/.github/labeler.yml
similarity index 100%
rename from .github/autolabeler.yml
rename to .github/labeler.yml

.github/workflows/labeler.yml

diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
new file mode 100644
index 0000000..23956a0
--- /dev/null
+++ b/.github/workflows/labeler.yml
@@ -0,0 +1,11 @@
+name: "Pull Request Labeler"
+on:
+- pull_request_target
+
+jobs:
+  triage:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/labeler@main
+      with:
+        repo-token: "${{ secrets.GITHUB_TOKEN }}"