forgejo: Check the aarch64 assembly indentation as part of the lint job

Alternatively, this could be a separate job, potentially keyed
to only run on PRs that touch files matching */aarch64/*. But
as this runs very quickly, it's probably less clutter to just
bundle it here.

.forgejo/workflows/lint.yml

@@ -24,3 +24,5 @@ jobs:
           key: pre-commit-${{ steps.install.outputs.envhash }}
       - name: Run pre-commit CI
         run: ~/pre-commit/bin/pre-commit run -c .forgejo/pre-commit/config.yaml --show-diff-on-failure --color=always --all-files
+      - name: Check aarch64 assembly indentation
+        run: ./tools/check_arm_indent.sh