if a file or directory cannot be found use FileNotFoundError

See https://docs.python.org/3/library/exceptions.html

mpsd-software-environment.py

@@ -173,13 +173,13 @@ def get_release_info(mpsd_release: str, script_dir: Path) -> Tuple[str, str, Lis
       toolchains for the release.
 
     Raises:
-    - Exception: If the release directory does not exist. Run `create_dir_structure()`
+    - FileNotFoundError: If the release directory does not exist. Run `create_dir_structure()`
       first.
     """
     # Get the info for release
     release_base_dir = script_dir / mpsd_release
     if not os.path.exists(release_base_dir):
-        raise Exception(
+        raise FileNotFoundError(
             "Release directory does not exist. Run create_dir_structure() first."
         )
     with os_chdir(release_base_dir):