[build] Ensure `compat._legacy` is packed in executables

Fixes https://github.com/yt-dlp/yt-dlp/commit/9196cbfe8bb7a6eb46037735b76f21963dfdc61a#commitcomment-72192406

pyinst.py

@@ -47,6 +47,7 @@ def main():
         '--noconfirm',
         *dependency_options(),
         *opts,
+        '--collect-submodules=yt_dlp',
         'yt_dlp/__main__.py',
     ]
     print(f'Running PyInstaller with {opts}')

setup.py

@@ -48,6 +48,8 @@
                 'dist_dir': './dist',
                 'excludes': ['Crypto', 'Cryptodome'],  # py2exe cannot import Crypto
                 'dll_excludes': ['w9xpopen.exe', 'crypt32.dll'],
+                # Modules that are only imported dynamically must be added here
+                'includes': ['yt_dlp.compat._legacy'],
             }
         },
         'zipfile': None