update go version to 1.22

[mollykarcher]

What problem does your feature solve?

The current/most recent version of golang is 1.22, and we are currently testing and building with version 1.20. Golang will only issue security patches/releases for the two most recent versions of golang. So if any are released, we are missing out on patches for those due to the older version we're using.

What would you like to see?

Update all relevant repos and built packages/images to use go 1.22

• go monorepo (github CI workflows, Dockerfiles, go.mod, etc etc)
• soroban-rpc (github CI workflows, Dockerfiles, go.mod, etc etc)
• pipelines/package builders (https://github.com/stellar/pipelines) for both Horizon and RPC
• quickstart https://github.com/stellar/quickstart