Add version metadata and --version command

pr_agent/version.py

@@ -0,0 +1,23 @@
+import os
+import sys
+from importlib.metadata import version, PackageNotFoundError
+
+from pr_agent.log import get_logger
+
+def get_version() -> str:
+    # First check pyproject.toml if running directly out of repository
+    if os.path.exists("pyproject.toml"):
+        if sys.version_info >= (3, 11):
+            import tomllib
+            with open("pyproject.toml", "rb") as f:
+                data = tomllib.load(f)
+                return data["project"]["version"]
+        else:
+            get_logger().warn("Unable to determine local version from pyproject.toml")
+
+    # Otherwise get the installed pip package version
+    try:
+        return version('pr-agent')
+    except PackageNotFoundError:
+        get_logger().error("Unable to find package named 'pr-agent'")
+        return "unknown"