ruby: make a predicate private

Author: alexrford

ruby/ql/lib/codeql/ruby/frameworks/rack/internal/Mime.qll

@@ -1,7 +1,7 @@
 private import codeql.ruby.ApiGraphs
 private import codeql.ruby.DataFlow
 
-predicate mimeTypeMatches(string ext, string mimeType) {
+private predicate mimeTypeMatches(string ext, string mimeType) {
   ext = ".123" and mimeType = "application/vnd.lotus-1-2-3"
   or
   ext = ".3dml" and mimeType = "text/vnd.in3d.3dml"