allow to overwrite encryption settings

Author: mprzytulski

serverless/aws/resources/s3.py

@@ -46,7 +46,7 @@ def __init__(self, BucketName="${self:service}", domain=None, ForceName=False, *
     def configure(self, service):
         super().configure(service)
 
-        if service.has(Encryption):
+        if service.has(Encryption) and getattr(self.resource, "BucketEncryption", None) is None:
             self.resource.BucketEncryption = BucketEncryption(
                 ServerSideEncryptionConfiguration=[
                     ServerSideEncryptionRule(