WX-1445 Update docker image regex to handle python:3 correctly (#7367)

Author: jgainerdewar

dockerHashing/src/main/scala/cromwell/docker/DockerImageIdentifier.scala

@@ -56,7 +56,7 @@ object DockerImageIdentifier {
 
        (                                        # Begin capturing group for name
           [a-z0-9]+(?:[._-][a-z0-9]+)*          # API v2 name component regex - see https://docs.docker.com/registry/spec/api/#/overview
-          (?::[0-9]+)?                          # Optional port
+          (?::[0-9]{4,5}|:443)?                 # Optional port (expect 4 or 5 digits OR :443)
           (?:/[a-z0-9]+(?:[._-][a-z0-9]+)*)*    # Optional additional name components separated by /
        )                                        # End capturing group for name
 

dockerHashing/src/test/scala/cromwell/docker/DockerImageIdentifierSpec.scala

@@ -41,6 +41,8 @@ class DockerImageIdentifierSpec
        "0.8.1.1--htslib1.5_0"
       ),
       ("terrabatchdev.azurecr.io/postgres:latest", Option("terrabatchdev.azurecr.io"), None, "postgres", "latest"),
+      ("python:3", None, None, "python", "3"),
+      ("localhost:443/ubuntu", Option("localhost:443"), None, "ubuntu", "latest"),
       // Very long tags with trailing spaces cause problems for the re engine
       ("someuser/someimage:supercalifragilisticexpialidociouseventhoughthesoundofitissomethingquiteatrociousifyousayitloudenoughyoullalwayssoundprecocious ",
        None,