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.

setup.py

@@ -333,7 +333,7 @@ SPECIAL_SOURCES = {
 def newer(dest, *sources):
     try:
         dtime = os.path.getmtime(dest)
-    except EnvironmentError:
+    except OSError:
         return True
     for s in sources:
         with suppress(FileNotFoundError):