Apply suggestions from code review

Co-authored-by: Frames White <oxinabox@ucc.asn.au>

Author: nomadbl

Project.toml

@@ -14,10 +14,10 @@ StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 [compat]
 FileIO = "1.2.3"
 ImageCore = "0.8.1, 0.9"
-ProtoBuf = "0.10, 0.11, 1.0.11"
+ProtoBuf = "1.0.11"
 Requires = "0.5, 1"
 StatsBase = "0.27, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34"
-julia = "1.3, 1.9"
+julia = "1.6"
 
 [extras]
 Minio = "4281f0d9-7ae0-406e-9172-b7277c1efa20"