packaging: bump dulwich to 0.20.45 I'm told the new dulwich avoids hg-git test failures.

packaging: update keyring on Windows to avoid spurious stacktraces When challenged for a network password, this would spew on Windows before it actually used the stored password: ``` Error initializing plugin EntryPoint(name='libsecret', value='keyring.backends.libsecret', group='keyring.backends'). Traceback (most recent call last): File "keyring.backend", line 198, in _load_plugins init_func = ep.load() File "importlib.metadata", line 77, in load module = import_module(match.group('module')) File "importlib", line 127, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "<frozen importlib._bootstrap>", line 1030, in _gcd_import File "<frozen importlib._bootstrap>", line 1007, in _find_and_load File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked ModuleNotFoundError: No module named 'keyring.backends.libsecret' Error initializing plugin EntryPoint(name='macOS', value='keyring.backends.macOS', group='keyring.backends'). Traceback (most recent call last): File "keyring.backend", line 198, in _load_plugins init_func = ep.load() File "importlib.metadata", line 77, in load module = import_module(match.group('module')) File "importlib", line 127, in import_module return _bootstrap._gcd_import(name[level:], package, level) File "<frozen importlib._bootstrap>", line 1030, in _gcd_import File "<frozen importlib._bootstrap>", line 1007, in _find_and_load File "<frozen importlib._bootstrap>", line 984, in _find_and_load_unlocked ModuleNotFoundError: No module named 'keyring.backends.macOS' ``` We're kinda threading a needle here because the next version of `keyring` (currently at 23.7.0) requires `importlib-metadata` 3.6+, which PyOxidizer 0.22 doesn't support[1]. [1] https://github.com/indygreg/PyOxidizer/issues/609