Update .gitlab-ci.yml: the default python3 version was changed in the...
Update .gitlab-ci.yml: the default python3 version was changed in the ligo/base:el7 container, so the build dependencies had to be changed to reflect that.
Update .gitlab-ci.yml: the default python3 version was changed in the ligo/base:el7 container, so the build dependencies had to be changed to reflect that.