Add vault-plugin-secrets-gpg repository

The GPG/OpenPGP secrets engine needs a Gitea repo to hold its source and run
its Woodpecker PR/release pipelines.

- Add config/git.unkin.net/unkin/repository/vault-plugin-secrets-gpg.yaml
  (public, main default branch, squash-only, main branch protection gated on
  the pre-commit/build/test PR checks), mirroring the sibling
  vault-plugin-secrets-bind-tsig repo.

config/git.unkin.net/unkin/repository/vault-plugin-secrets-gpg.yaml

@@ -0,0 +1,19 @@
+description: "HashiCorp Vault / OpenBao secrets engine for GPG/OpenPGP keys (sign/verify/encrypt/decrypt, transit-style versioned keys, pass-compatible)"
+private: false
+default_branch: "main"
+default_delete_branch_after_merge: true
+# Squash-only: the gitea provider has no "default merge style", so we restrict
+# the allowed styles to squash to force it.
+allow_merge_commits: false
+allow_rebase: false
+allow_rebase_explicit: false
+allow_squash_merge: true
+branch_protection:
+  - rule_name: "main"
+    enable_push: false
+    status_check_contexts:
+      - "ci/woodpecker/pr/pre-commit"
+      - "ci/woodpecker/pr/build"
+      - "ci/woodpecker/pr/test"
+    approval_whitelist_teams:
+      - "Owners"