Switch Bazel WORKSPACE Go version to "host"

No need to hard-code a specific version, we can just use the host, which
will make it easy for folks to use with any version they have already
installed, and makes it easier to specify a different version via GitHub
Actions versions dynamically.

WORKSPACE

@@ -58,6 +58,6 @@ go_repository(
 
 go_rules_dependencies()
 
-go_register_toolchains(version = "1.17.6")
+go_register_toolchains(version = "host")
 
 gazelle_dependencies()