[AIRFLOW-2238] Use SSH protocol for pushing to Github (#3680)
[AIRFLOW-2238] Use SSH protocol for pushing to Github (#3680)

Since we have MFA enforced we won't be able to use passwords to push and
will have to use SSH keypairs.
adamhaney/airflow,andyxhadji/incubator-airflow,apache/incubator-airflow,nathanielvarona/airflow,fenglu-g/incubator-airflow,bolkedebruin/airflow,criccomini/airflow,bolkedebruin/airflow,apache/airflow,gtoonstra/airflow,danielvdende/incubator-airflow,mrkm4ntr/incubator-airflow,mistercrunch/airflow,mtagle/airflow,apache/incubator-airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,spektom/incubator-airflow,artwr/airflow,akosel/incubator-airflow,malmiron/incubator-airflow,nathanielvarona/airflow,apache/incubator-airflow,DinoCow/airflow,r39132/airflow,Acehaidrey/incubator-airflow,andyxhadji/incubator-airflow,fenglu-g/incubator-airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,akosel/incubator-airflow,artwr/airflow,mistercrunch/airflow,spektom/incubator-airflow,lyft/incubator-airflow,mrkm4ntr/incubator-airflow,apache/airflow,wileeam/airflow,wooga/airflow,dhuang/incubator-airflow,edgarRd/incubator-airflow,mtagle/airflow,bolkedebruin/airflow,Fokko/incubator-airflow,criccomini/airflow,dhuang/incubator-airflow,edgarRd/incubator-airflow,bolkedebruin/airflow,Fokko/incubator-airflow,cfei18/incubator-airflow,wileeam/airflow,jgao54/airflow,spektom/incubator-airflow,sid88in/incubator-airflow,apache/airflow,airbnb/airflow,gtoonstra/airflow,fenglu-g/incubator-airflow,wileeam/airflow,artwr/airflow,adamhaney/airflow,sekikn/incubator-airflow,edgarRd/incubator-airflow,danielvdende/incubator-airflow,mtagle/airflow,sid88in/incubator-airflow,fenglu-g/incubator-airflow,malmiron/incubator-airflow,mrkm4ntr/incubator-airflow,wileeam/airflow,cfei18/incubator-airflow,mtagle/airflow,apache/airflow,wooga/airflow,DinoCow/airflow,airbnb/airflow,malmiron/incubator-airflow,sid88in/incubator-airflow,artwr/airflow,jgao54/airflow,Fokko/incubator-airflow,adamhaney/airflow,apache/airflow,wooga/airflow,wooga/airflow,criccomini/airflow,adamhaney/airflow,airbnb/airflow,lyft/incubator-airflow,dhuang/incubator-airflow,nathanielvarona/airflow,mistercrunch/airflow,jgao54/airflow,lyft/incubator-airflow,Acehaidrey/incubator-airflow,lyft/incubator-airflow,cfei18/incubator-airflow,sekikn/incubator-airflow,sekikn/incubator-airflow,danielvdende/incubator-airflow,mrkm4ntr/incubator-airflow,jgao54/airflow,apache/airflow,andyxhadji/incubator-airflow,malmiron/incubator-airflow,sid88in/incubator-airflow,r39132/airflow,criccomini/airflow,sekikn/incubator-airflow,akosel/incubator-airflow,andyxhadji/incubator-airflow,DinoCow/airflow,nathanielvarona/airflow,airbnb/airflow,gtoonstra/airflow,nathanielvarona/airflow,r39132/airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,mistercrunch/airflow,danielvdende/incubator-airflow,apache/incubator-airflow,Fokko/incubator-airflow,bolkedebruin/airflow,spektom/incubator-airflow,Acehaidrey/incubator-airflow,dhuang/incubator-airflow,DinoCow/airflow,edgarRd/incubator-airflow,cfei18/incubator-airflow,gtoonstra/airflow,akosel/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,r39132/airflow