ci: Use go1.17 for lint/test until we officially support go1.18

[kamilogorek]

There are some changes required to support go1.18, and I want the CI to stay green until we make them.

[kamilogorek]

[Error: EEXIST: file already exists, mkdir '/home/runner/work/sentry-go/sentry-go/deps:/home'] {
  errno: -17,
  code: 'EEXIST',
  syscall: 'mkdir',
  path: '/home/runner/work/sentry-go/sentry-go/deps:/home'
}

wat