fix: Add default values to config classes to resolve test validation errors

- Add default instances to all nested config classes (TorrentConfig, NotificationConfig, IndexerConfig, MetadataProviderConfig, AuthConfig)
- Add default values to AllEncompassingConfig fields to prevent validation errors during testing
- Update GitHub workflow to copy config.example.toml before running tests
- Ensures tests can run without requiring complete configuration files while maintaining production functionality

Fixes test collection errors where pydantic validation failed due to missing required config sections.

media_manager/metadataProvider/config.py

@@ -10,5 +10,5 @@ class TvdbConfig(BaseSettings):
 
 
 class MetadataProviderConfig(BaseSettings):
-    tvdb: TvdbConfig
-    tmdb: TmdbConfig
+    tvdb: TvdbConfig = TvdbConfig()
+    tmdb: TmdbConfig = TmdbConfig()