Add setting to disable posting of commit statuses

Useful for testing.

src/runboat/github.py

@@ -64,6 +64,8 @@ class GitHubStatusState(str, Enum):
 async def notify_status(
     repo: str, sha: str, state: GitHubStatusState, target_url: str | None
 ) -> None:
+    if settings.disable_commit_statuses:
+        return
     # https://docs.github.com/en/rest/reference/repos#create-a-commit-status
     await _github_request(
         "POST",

src/runboat/settings.py

@@ -58,6 +58,8 @@ class Settings(BaseSettings):
     base_url: str = "http://localhost:8000"
     # HTML fragment for second footer.
     additional_footer_html: str = ""
+    # Disable posting of statuses to GitHub commits
+    disable_commit_statuses: bool = False
 
     def get_build_settings(self, repo: str, target_branch: str) -> list[BuildSettings]:
         for repo_settings in self.repos: