Updates go.mod / ci / dependabot config

[cpanato]

• update go mod to go1.21
• update ci actions and test with supported go versions
• add dependabot config for github actions

[wlynch]

Thanks @cpanato!

TBD on the go.mod bump for now (See #120 (review)) - if you want to revert that I can merge the rest! (newer go versions should still be able to handle the older go.mod).

[cpanato]

Thanks @cpanato!

TBD on the go.mod bump for now (See #120 (review)) - if you want to revert that I can merge the rest! (newer go versions should still be able to handle the older go.mod).

yes, but when I reverted and ran the go mod tidy, I added the toolchain to 1.22.3 and bumped the definition to 1.21 automatically, then i manualy reverted that and push the commit