Add support for IA_S3_{ACCESS,SECRET} environment variables

ia-upload-stream

@@ -41,6 +41,9 @@ class PreventCompletionError(UploadError):
 
 
 def get_ia_access_secret(configFile = None):
+	if 'IA_S3_ACCESS' in os.environ and 'IA_S3_SECRET' in os.environ:
+		return os.environ['IA_S3_ACCESS'], os.environ['IA_S3_SECRET']
+
 	if configFile is None:
 		# This part of the code is identical (except for style changes) to the one in internetarchive and was written from scratch by JustAnotherArchivist in May and December 2021.
 		candidates = []