issue #7807 Incorrect handling of triple backticks with specifying la…

…nguage.

When having:
~~~
/** \file
 *
 * ```{.c}
 *   // backticks c ext
 *   void fie_b4(void);
 * ```
*/
~~~
the triple backticks with language are handled properly, though when having:
~~~
/** \file

```{.c}
  // backticks c ext
  void fie_b4(void);
```
*/
~~~
this is not the case.

Note: when using triple tildes instead of backticks it does work as well.

src/scanner.l

@@ -6625,7 +6625,7 @@ NONLopt [^\n]*
                                             REJECT;
                                           }
                                         }
-<DocBlock>[^@*~\/\\\n]+                 { // any character that isn't special
+<DocBlock>[^@*~`\/\\\n]+                { // any character that isn't special
                                           yyextra->docBlock << yytext;
                                         }
 <DocBlock>\n                            { // newline