sigrokdriver: fix TypeError in stop() by passing bytes to communicate()

Popen is opened without text=True so stdin is in binary mode.
communicate(input=...) must receive bytes, not str.
Fixes Python 3.11+ TypeError: memoryview requires bytes, not str.

Fixes #1847

Signed-off-by: xistadi <xistadi@users.noreply.github.com>

Author: xistadi

labgrid/driver/sigrokdriver.py

@@ -175,7 +175,7 @@ def stop(self):
         csv_filename = f'{os.path.splitext(self._basename)[0]}.csv'
 
         # sigrok-cli can be quit through any keypress
-        stdout, stderr = self._process.communicate(input="q")
+        stdout, stderr = self._process.communicate(input=b"q")
         self.logger.debug("stdout: %s", stdout)
         self.logger.debug("stderr: %s", stderr)