Simplify TestProgram._get_runner

This try-except was necessary to support an instance of a runner being
passed that did not support the `tb_locals` parameter. This appears to
be a compat handler for Python 2.x variants of `TextTestRunner`, which
did not accept this parameter [1]. This is not the case of the lowest
version of Python we currently support, 3.10 [2], meaning we can remove
the wrapper.

[1] https://github.com/python/cpython/blob/v2.7.1/Lib/unittest/runner.py#L127-L128
[2] https://github.com/python/cpython/blob/v3.10.0/Lib/unittest/runner.py#L128-L130

Signed-off-by: Stephen Finucane <stephen@that.guru>

Author: stephenfin

testtools/run.py

@@ -267,22 +267,13 @@ def _get_runner(self) -> TestToolsTestRunner:
 
         runner_factory: Callable[..., TestToolsTestRunner] = runner_or_factory
         try:
-            try:
-                testRunner = runner_factory(
-                    verbosity=self.verbosity,
-                    failfast=self.failfast,
-                    buffer=self.buffer,
-                    stdout=self.stdout,
-                    tb_locals=self.tb_locals,
-                )
-            except TypeError:
-                # didn't accept the tb_locals parameter
-                testRunner = runner_factory(
-                    verbosity=self.verbosity,
-                    failfast=self.failfast,
-                    buffer=self.buffer,
-                    stdout=self.stdout,
-                )
+            testRunner = runner_factory(
+                verbosity=self.verbosity,
+                failfast=self.failfast,
+                buffer=self.buffer,
+                stdout=self.stdout,
+                tb_locals=self.tb_locals,
+            )
         except TypeError:
             # didn't accept the verbosity, buffer, failfast or stdout arguments
             try: