feat: AWS Secrets Manager support

tests/providers/provider_tests.rs

@@ -1,14 +1,6 @@
 use gman::config::ProviderConfig;
-use gman::providers::ParseProviderError;
-use pretty_assertions::assert_eq;
 use validator::Validate;
 
-#[test]
-fn test_parse_provider_error_display() {
-    let err = ParseProviderError::Unsupported("test".to_string());
-    assert_eq!(err.to_string(), "unsupported provider 'test'");
-}
-
 #[test]
 fn test_provider_config_missing_name() {
     let config = ProviderConfig {