Updated python runtime version from 3.6 to 3.9

Author: Gregory Davis

ImageProcessing/workshop/static/cloudformation/sam_220615.yaml

@@ -127,7 +127,7 @@ Resources:
           - Fn::Sub: arn:aws:s3:::${ThumbnailS3Bucket}
           - Fn::Sub: arn:aws:s3:::${ThumbnailS3Bucket}/*
           Sid: DestBucketWriteAccess
-      Runtime: python3.6
+      Runtime: python3.9
       Timeout: 120
     Type: AWS::Serverless::Function
   EmptyThumbnailBucket: