ultralytics 8.0.21 Windows, segments, YAML fixes (#655)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: corey-nm <109536191+corey-nm@users.noreply.github.com>

ultralytics/yolo/utils/checks.py

@@ -207,9 +207,9 @@ def check_file(file, suffix=''):
     # Search/download file (if necessary) and return path
     check_suffix(file, suffix)  # optional
     file = str(file)  # convert to str()
-    if Path(file).is_file() or not file:  # exists
+    if not file or ('://' not in file and Path(file).is_file()):  # exists ('://' check required in Windows Python<3.10)
         return file
-    elif file.startswith(('http:/', 'https:/')):  # download
+    elif file.lower().startswith(('https://', 'http://', 'rtsp://', 'rtmp://')):  # download
         url = file  # warning: Pathlib turns :// -> :/
         file = Path(urllib.parse.unquote(file).split('?')[0]).name  # '%2F' to '/', split https://url.com/file.txt?auth
         if Path(file).is_file():
@@ -276,7 +276,7 @@ def git_describe(path=ROOT):  # path must be a directory
     try:
         assert (Path(path) / '.git').is_dir()
         return check_output(f'git -C {path} describe --tags --long --always', shell=True).decode()[:-1]
-    except Exception:
+    except AssertionError:
         return ''