Replace all instances of EnvironmentError with OSError

According to the text just above https://docs.python.org/3/library/exceptions.html#EnvironmentError, `EnvironmentError` has been an alias of `OSError` since Python 3.3. Replacing it makes the code more consistent since `OSError` is used in other places in the code too.

logo/make.py

@@ -17,7 +17,7 @@ def abspath(x):
 def run(*args):
     try:
         subprocess.check_call(args)
-    except EnvironmentError:
+    except OSError:
         raise SystemExit('You are missing the {} program needed to generate the kitty logo'.format(args[0]))