fix: fix the regex in Versions.java to actually split on '.' (#57)

Author: dpcollins-google

google-cloud-pubsublite/src/main/java/com/google/cloud/pubsublite/internal/wire/Versions.java

@@ -25,7 +25,7 @@ private Versions() {}
   private static String[] GetVersionSplits() {
     try {
       String versionString = GaxProperties.getLibraryVersion(Versions.class);
-      return versionString.split(".");
+      return versionString.split("\\.");
     } catch (Exception e) {
       return new String[0];
     }