fix(golangci-lint): version bump and location fix

[lc525]

Change location where scheduler/Makefile downloads golangci-lint. Previous location name conflicts with any previously installed golangci-lint.

Specifically, the Makefile used to install it in ${GOPATH}/bin/golangci-lint/[VERSION]/ however, this means that the ${GOPATH}/bin/golangci-lint file can not exist at the same time. The latter is the default install path when installing via go install.

The new location for the seldon downloaded golangci-lint is ${GOPATH}/bin/golangci-lint-versions/[VERSION]/