Drop dependency on disutils (#1544)

* Drop dependency on distutils

While distutils is part of stdlib, it feels odd to use distutils in main application code.

I personally use a (lean)[https://hub.docker.com/r/haizaar/python-minimal/tags] Python distribution for running my applications that does not include distutils.

* Flake8 fixes

* "black" fixes

* strtobool should actually return bool

sanic/config.py

@@ -1,8 +1,6 @@
 import os
 import types
 
-from distutils.util import strtobool
-
 from sanic.exceptions import PyFileError
 
 
@@ -127,6 +125,23 @@ class Config(dict):
                         self[config_key] = float(v)
                     except ValueError:
                         try:
-                            self[config_key] = bool(strtobool(v))
+                            self[config_key] = strtobool(v)
                         except ValueError:
                             self[config_key] = v
+
+
+def strtobool(val):
+    """
+    This function was borrowed from distutils.utils. While distutils
+    is part of stdlib, it feels odd to use distutils in main application code.
+
+    The function was modified to walk its talk and actually return bool
+    and not int.
+    """
+    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("invalid truth value %r" % (val,))