chore(github): point labeler and dependabot at the de-emojied label names

The repo carried two label vocabularies: the emoji-suffixed libretro
defaults (`bug 🐛`, `enhancement 🧰`, `ci/cd 🤖`) and the
clean names added later (`accuracy`, `epic`, `size: *`, `no-code`).

The issue templates were already written against the clean names --
`bug_report.yml` asks for `bug`, `feature_request.yml` for `enhancement` --
and neither label existed.  GitHub applies nothing and reports nothing in
that case, so every templated bug report and feature request has been
landing unlabelled.

Labels renamed on the repo to the clean names (renames preserve every
assignment); this commit updates the two files that referenced the old
ones.  Also creates `dependencies`, which dependabot.yml has been asking
for without it existing either.

Co-Authored-By: Claude Opus 5 <[email protected]>

.github/dependabot.yml

@@ -14,7 +14,7 @@ updates:
       timezone: "America/New_York"
     open-pull-requests-limit: 5
     labels:
-      - "ci/cd :robot:"
+      - "ci"
       - "dependencies"
     commit-message:
       prefix: "ci"

.github/labeler.yml

@@ -90,7 +90,7 @@ build:
       - 'scripts/**'
       - 'jni/Android.mk'
 
-"ci/cd :robot:":
+ci:
   - changed-files:
     - any-glob-to-any-file:
       - '.github/workflows/**'
@@ -104,7 +104,7 @@ build:
       - 'gcovr.cfg'
       - 'codecov.yml'
 
-":book: documentation":
+documentation:
   - changed-files:
     - any-glob-to-any-file:
       - '**/*.md'