v1.4: Minor speed improvements, dependency updates

What's Changed

• docker: speed up by not downloading curl by @srvaroa in #72
• Bump github.com/google/go-github/v50 from 50.0.0 to 50.1.0 by @dependabot in #74
• Bump golang.org/x/oauth2 from 0.0.0-20180821212333-d2e6202438be to 0.5.0 by @dependabot in #73
• Bump golang.org/x/oauth2 from 0.5.0 to 0.6.0 by @dependabot in #75
• Bump golang.org/x/crypto from 0.0.0-20210817164053-32db794688a5 to 0.1.0 by @dependabot in #76