Remove check for "frozen" when setting the keyring backend

There is no need to have a different behavior from source compared to frozen builds when it comes to the keyring.

CURA-8490

cura/OAuth2/KeyringAttribute.py

@@ -14,14 +14,14 @@ if TYPE_CHECKING:
 # Need to do some extra workarounds on windows:
 import sys
 from UM.Platform import Platform
-if Platform.isWindows() and hasattr(sys, "frozen"):
+if Platform.isWindows():
     import win32timezone
     from keyring.backends.Windows import WinVaultKeyring
     keyring.set_keyring(WinVaultKeyring())
-if Platform.isOSX() and hasattr(sys, "frozen"):
+if Platform.isOSX():
     from keyring.backends.macOS import Keyring
     keyring.set_keyring(Keyring())
-if Platform.isLinux() and hasattr(sys, "frozen"):
+if Platform.isLinux():
     # We do not support the keyring on Linux, so make sure no Keyring backend is loaded, even if there is a system one.
     from keyring.backends.fail import Keyring as NoKeyringBackend
     keyring.set_keyring(NoKeyringBackend())