remove patching instructions for cumin

The patches don't apply against the latest release and appear to be
rendered obsolete since the fixes have been merged upstream and
released.

howto/cumin.md

@@ -25,12 +25,7 @@ First, install dependencies, Cumin and some patches:
     ~/.virtualenvs/cumin/bin/pip3 uninstall tqdm pyparsing clustershell # force using trusted system packages
 
 Notice how Cumin is installed in a [Python virtualenv][]: it is not
-yet [in Debian][]. You'll also need a patch to enable plain HTTP
-access, see [this bug report][]. You might also want to disable the
-[root check][] as well:
-
-    git clone https://github.com/wikimedia/cumin/ &&
-    git -C cumin show 8e49a21f57583f5c229ba05a0828d810b3543088 26aaf06950cf22850252785d689b34c54acd9785 | ( cd ~/.virtualenvs/cumin/lib/python3.7/site-packages && patch -p1 -f )
+yet [in Debian][].
 
 Then drop the following configuration in
 `~/.config/cumin/config.yaml`: