Fix GitHub Workflow publish branches.

Issue: #17

Author: steinybot

build.sbt

@@ -78,7 +78,7 @@ inThisBuild(
     ),
     // TODO: #17 - Fix main snapshot release.
     //githubWorkflowPublishTargetBranches += RefPredicate.StartsWith(Ref.Tag("v")),
-    githubWorkflowPublishTargetBranches := RefPredicate.StartsWith(Ref.Tag("v")),
+    githubWorkflowPublishTargetBranches := List(RefPredicate.StartsWith(Ref.Tag("v"))),
     githubWorkflowTargetTags ++= List("v*"),
     pgpSigningKey := Some("0x8DB7DFA142551359!"),
     // This needs to be set otherwise the GitHub workflow plugin gets confused about which