commit(s) to merge: 4b3840d

merge instructions: clean merge

What is the issue: Packages without lower-bound SDK constraint are broken.

What is the fix: Adds default language version 2.7 when there is no lower-bound SDK constraint in dependencies.

Link to original issue(s): #44013 (comment)

/cc @kevmoo @mit-mit @whesse @athomas @vsmenon @franklinyow