fix: global interpreter was used in subprocess instead of venv

src/khalorg/khal/helpers.py

@@ -1,4 +1,5 @@
 import logging
+import sys
 from datetime import date, datetime
 from subprocess import STDOUT, CalledProcessError, check_output
 from typing import Callable
@@ -56,6 +57,7 @@ def subprocess_callback(cmd: list) -> Callable:
         callback function
 
     """
+
     def callback(args: list) -> str:
         return try_check_output([*cmd, *args]).decode()
 
@@ -64,12 +66,13 @@ def callback(args: list) -> str:
 
 def try_check_output(args: list) -> bytes:
     try:
-        return check_output(args, stderr=STDOUT)
+        return check_output(args, stderr=STDOUT, executable=sys.executable)
     except CalledProcessError as error:
         error_message: str = (
             f"The following arguments were sent to khal:\n\n{' '.join(args)}"
             "\n\nNext, the following error was received from khal:\n\n"
-            f"{error.output.decode()}\n\n")
+            f"{error.output.decode()}\n\n"
+        )
         logging.critical(error_message)
         raise Exception(error_message) from error