A bug in svntest\main.py makes all py tests failed with -enable-sasl

[VirusCamp]

Hi, everyone.
I found a bug in subversion-1.14.2\subversion\tests\cmdline\svntest\main.py.
The bug makes `python win-tests.py --enable-sasl` failed for all py tests.

```
Traceback (most recent call last):
  File "D:\subversion-1.14.2\subversion\tests\cmdline\svntest\main.py",
line 1927, in run
    rc = self.pred.run(sandbox)
  File "D:\subversion-1.14.2\subversion\tests\cmdline\svntest\testcase.py",
line 258, in run
    return self._delegate.run(sandbox)
  File "D:\subversion-1.14.2\subversion\tests\cmdline\svntest\testcase.py",
line 178, in run
    result = self.func(sandbox)
  File "D:\subversion-1.14.2\subversion\tests\cmdline\authz_tests.py", line
68, in authz_open_root
    write_restrictive_svnserve_conf(sbox.repo_dir)
  File "D:\subversion-1.14.2\subversion\tests\cmdline\svntest\main.py",
line 1362, in write_restrictive_svnserve_conf
    fp.write("realm = svntest\n"
TypeError: TextIOWrapper.write() takes exactly one argument (2 given)
FAIL:  authz_tests.py 1: authz issue #2486 - open root
END: authz_tests.py
ELAPSED: authz_tests.py 0:00:11.813435
```

Please fix it by edit
subversion-1.14.2\subversion\tests\cmdline\svntest\main.py , and remove the
marked comma.
```python
def write_restrictive_svnserve_conf(repo_dir, anon_access="none",
                                    separate_groups_db=False):
  ....
  if options.enable_sasl:
    fp.write("realm = svntest\n"
             "[sasl]\n",  # remove the comma
             "use-sasl = true\n");
```