Update to Go 1.14 for build-go1.x image

Update build-python3.6 to Python 3.6.10

Lock virtualenv in build-python2.7 image

Update build-python3.6 to Python 3.6.10

Update build images to aws-sam-cli 0.43.0

Update build images to aws-sam-cli 0.43.0

Update build images to aws-sam-cli 0.43.0

Update build images to aws-sam-cli 0.43.0

Update build images to aws-sam-cli 0.43.0

Update build images to aws-sam-cli 0.43.0