Declare go-cache-plugin build repo

Adds the Gitea repo that builds and releases the tailscale go-cache-plugin
GOCACHEPROG binary for the estate.

config/git.unkin.net/unkin/repository/go-cache-plugin.yaml

@@ -0,0 +1,16 @@
+description: "Build repo that compiles the tailscale/go-cache-plugin GOCACHEPROG S3 Go build cache from a pinned upstream module version and publishes static binaries as Gitea releases."
+private: false
+default_branch: "main"
+default_delete_branch_after_merge: true
+default_merge_style: "squash"
+branch_protection:
+  - rule_name: "main"
+    merge_whitelist_teams:
+      - "Owners"
+    enable_push: false
+    status_check_contexts:
+      - "ci/woodpecker/pr/build"
+      - "ci/woodpecker/pr/test"
+      - "ci/woodpecker/pr/pre-commit"
+    approval_whitelist_users:
+      - "benvin"