Replace deprecated strtobool function

app/grandchallenge/core/utils/__init__.py

@@ -1,4 +1,3 @@
-from distutils.util import strtobool as strtobool_i
 from functools import wraps
 
 
@@ -16,6 +15,17 @@ def wrapper(*args, **kwargs):
     return wrapper
 
 
-def strtobool(val) -> bool:
-    """Return disutils.util.strtobool as a boolean."""
-    return bool(strtobool_i(val))
+def strtobool(val):
+    """Convert a string representation of truth to true or false.
+
+    True values are 'y', 'yes', 't', 'true', 'on', and '1'; false values
+    are 'n', 'no', 'f', 'false', 'off', and '0'.  Raises ValueError if
+    'val' is anything else.
+    """
+    val = val.lower()
+    if val in ("y", "yes", "t", "true", "on", "1"):
+        return True
+    elif val in ("n", "no", "f", "false", "off", "0"):
+        return False
+    else:
+        raise ValueError(f"invalid truth value {val}")