fix: follow the act move in the paths outside Go code

`make test-dind` runs a hardcoded package path, and the `.gitignore`
negation for the test secrets fixture stopped matching.

Assisted-by: Codet:GPT-5.1-Codex

.gitignore

@@ -1,6 +1,6 @@
 /gitea-runner
 .env
-!/act/runner/testdata/secrets/.env
+!/internal/act/runner/testdata/secrets/.env
 .runner
 .runner.lock
 coverage.txt
@@ -14,4 +14,4 @@ coverage.txt
 __debug_bin
 # gorelease binary folder
 /dist
-.DS_Store
+.DS_Store