Refactor latest.py and update.py (#270)

- create new gha.py module,
- improve GitHub workflow commands (GITHUB_OUTPUT, GITHUB_STEP_SUMMARY) interactions,
- improve logging,
- split update.py into smaller functions.

src/common/gha.py

@@ -0,0 +1,47 @@
+import logging
+import os
+from base64 import b64encode
+
+"""See https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions."""
+
+
+class GitHubOutput:
+    def __init__(self, name: str) -> None:
+        self.name = name
+        self.value = ""
+
+    def __enter__(self) -> None:
+        return None
+
+    def println(self, value: str) -> None:
+        self.value += value + "\n"
+
+    def __exit__(self, exc_type: any, exc_value: any, traceback: any) -> None:
+        var_exists = "GITHUB_OUTPUT" in os.environ
+        delimiter = b64encode(os.urandom(16)).decode()
+        value = f"{delimiter}\n{self.value}\n{delimiter}"
+        command = f"{self.name}<<{value}"
+
+        logging.info(f"GITHUB_OUTPUT (exists={var_exists}):\n{command}")
+        if var_exists:
+            with open(os.environ["GITHUB_OUTPUT"], 'a') as github_output_var:  # NOQA: PTH123
+                print(command, file=github_output_var)
+
+
+class GitHubStepSummary:
+    def __init__(self) -> None:
+        self.value = ""
+
+    def __enter__(self) -> None:
+        return None
+
+    def println(self, value: str) -> None:
+        self.value += value + "\n"
+
+    def __exit__(self, exc_type: any, exc_value: any, traceback: any) -> None:
+        var_exists = "GITHUB_STEP_SUMMARY" in os.environ
+
+        logging.info(f"GITHUB_STEP_SUMMARY (exists={var_exists}):\n{self.value}")
+        if var_exists:
+            with open(os.environ["GITHUB_STEP_SUMMARY"], 'a') as github_step_summary:  # NOQA: PTH123
+                print(self.value, file=github_step_summary)