Update Go version to 1.21 and sync package

Changelog for 0.1.0:

• PR #13 Bump golang.org/x/sync from 0.3.0 to 0.4.0 by @dependabot[bot]
• PR #10 Bump docker/login-action from 2 to 3 by @dependabot[bot]
• PR #11 Bump docker/setup-buildx-action from 2 to 3 by @dependabot[bot]
• PR #12 Bump docker/setup-qemu-action from 2 to 3 by @dependabot[bot]
• PR #9 Bump golang.org/x/sync from 0.2.0 to 0.3.0 by @dependabot[bot]

Commits
a2c5e5f Cancel inflight builds by @alexellis
d31304d Update Go build for Dockerfile by @alexellis
310bb3e Update Go version for build by @alexellis
7287157 Update README.md by @alexellis
6e2d27f Bump golang.org/x/sync from 0.3.0 to 0.4.0 by @dependabot[bot]
1d24f28 Bump docker/login-action from 2 to 3 by @dependabot[bot]
868bdda Bump docker/setup-buildx-action from 2 to 3 by @dependabot[bot]
bb67b8b Bump docker/setup-qemu-action from 2 to 3 by @dependabot[bot]
6369eca Bump golang.org/x/sync from 0.2.0 to 0.3.0 by @dependabot[bot]

Changes: 0.0.3...0.1.0

Generated by Derek