delete outdated deprecations

java/ql/lib/semmle/code/java/regex/RegexTreeView.qll

@@ -1162,14 +1162,6 @@ module Impl implements RegexTreeViewSig {
     root.getLiteral().isIgnoreCase()
   }
 
-  /**
-   * Gets the flags for `root`, or the empty string if `root` has no flags.
-   */
-  additional deprecated string getFlags(RegExpTerm root) {
-    root.isRootTerm() and
-    result = root.getLiteral().getFlags()
-  }
-
   /**
    * Holds if `root` has the `s` flag for multi-line matching.
    */