Fixes the regex pattern used for regex extraction

Author: spacether

modules/openapi-json-schema-generator/src/main/java/org/openapitools/codegen/languages/PythonClientCodegen.java

@@ -1895,7 +1895,7 @@ private String toExampleValueRecursive(String modelName, Schema schema, Object o
                 RxGen does not support our ECMA dialect https://github.com/curious-odd-man/RgxGen/issues/56
                 So strip off the leading / and trailing / and turn on ignore case if we have it
                  */
-                Pattern valueExtractor = Pattern.compile("^/?(.+?)/?(.?)$");
+                Pattern valueExtractor = Pattern.compile("^/?(.+?)/?([gim]?)$");
                 Matcher m = valueExtractor.matcher(pattern);
                 RgxGen rgxGen = null;
                 if (m.find()) {