chore: bump hard-coded version to v0.3.1

Author: philpennock

internal/version/version.go

@@ -8,7 +8,7 @@ package version
 //
 // This should be "latest release + 0.0.1 with -dev suffix"
 // OR if at the point where we're tagging, then that explicit tag.
-const HARDCODED_VERSION = "v0.3.1-dev"
+const HARDCODED_VERSION = "v0.3.1"
 
 // Set by ldflags at build time.
 var (