Mininal checker to simply control that the python project is working

Related to https://github.com/geoadmin/mf-chsdi3/issues/801
On 22.6, it has been observed several BadStatusLine error issued by the checker. One of them caused (at least was timely concurrent) a downtime of the print on the 23.6 at 00h23:50. 
The checker is currently used by all the proxies, which make 4 concurrent requests. The checker makes a request in order to check the root of the project mf-chsdi3. This kind of loop is probably not ideal. This PR proposes to make the checker very minimal and control only that the python project is available. It's clear that it doesn't mean that mf-chsdi3 is completely functional (it needs DB, sphinxsearh, access to FS), but it would be an overhead to check all these ressources every minute. These ressources have to be checked separately (which is the case with NAGIOS)