Change logging to match GitHub Actions messages

I've changed the logging format to match the format of Github Actions
messages. This means that logging messages, which will only be emitted
sparingly in production, will be added as annotations to the workflow to
make them obvious to the end user.

Note: logging.INFO level messages will get the label "debug", as Github
Actions only has three levels: debug, warning, error.

github_status_embed/log.py

@@ -10,7 +10,7 @@ def __init__(self, *args, masked_values: typing.Sequence[str], **kwargs) -> None
         super().__init__(*args, **kwargs)
         self._masked_values = masked_values
 
-    def format(self, record: logging.LogRecord) -> None:
+    def format(self, record: logging.LogRecord) -> str:
         """Emit a logging record after masking certain values."""
         message = super().format(record)
         for masked_value in self._masked_values:
@@ -24,9 +24,14 @@ def setup_logging(level: int, masked_values: typing.Sequence[str]) -> None:
     root = logging.getLogger()
     root.setLevel(level)
 
+    logging.addLevelName(logging.DEBUG, 'debug')
+    logging.addLevelName(logging.INFO, 'debug')  # GitHub Actions does not have an "info" message
+    logging.addLevelName(logging.WARNING, 'warning')
+    logging.addLevelName(logging.ERROR, 'error')
+
     handler = logging.StreamHandler(sys.stdout)
     formatter = MaskingFormatter(
-        '%(asctime)s :: %(name)s :: %(levelname)s :: %(message)s',
+        '::%(levelname)s::%(message)s',
         datefmt="%Y-%m-%d %H:%M:%S",
         masked_values=masked_values,
     )