Update Docker files for newer builder

[DiegoPino]

Getting things like this. We might need to update everywhere our use of ENV

3 warnings found (use docker --debug to expand):

• LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 54)
• NoEmptyContinuation: Empty continuation line (line 40)
• LegacyKeyValueFormat: "ENV key=value" should be used instead of legacy "ENV key value" format (line 16)