Add -V/--version option to display version

Signed-off-by: Martin Prpič <martin.prpic@gmail.com>

Author: mprpic

src/commit_editor/cli.py

@@ -1,5 +1,6 @@
 import argparse
 import sys
+from importlib.metadata import version
 from pathlib import Path
 
 
@@ -9,6 +10,12 @@ def main() -> int:
         prog="commit-editor",
         description="A terminal-based git commit message editor with opinionated formatting",
     )
+    parser.add_argument(
+        "-V",
+        "--version",
+        action="version",
+        version=f"%(prog)s {version('commit-editor')}",
+    )
     parser.add_argument(
         "filename",
         type=Path,