build: disable Go version check on macOS builds for TeamCity
build: disable Go version check on macOS builds for TeamCity

We run `xgo` directly on TeamCity agents (not in a Docker image), which
don't have a Go toolchain. This fails the Makefile's Go version check,
even though we're going to build with the xgo toolchain anyway. So this
commit disable the version check in build/build-osx.sh to unbrick TC
release builds.

Fixes #14104.

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