Enhance Renovate configuration

[Ido David (ido-namely)]

• Manage more dependencies with Renovate
• Group gateway go package separately (we avoid upgrading this package atm because of a breaking change regarding fieldmasks)
• Manage gateway go.mod template using Renovate's Go data source
• Remove go.sum.template (no need for it since the go app is vendored anew in the generated docker file).

[Steve Ognibene (nycdotnet)]

Would you please make a small update to the readme discussing what Renovate is and how this project uses it? There is a link to it in the readme already but a few sentences to guide someone like me who may be interested to use the tooling you've set up but isn't quite sure where to get started (some typical commands for example) would be very helpful.

[Ido David (ido-namely)]

Would you please make a small update to the readme discussing what Renovate is and how this project uses it? There is a link to it in the readme already but a few sentences to guide someone like me who may be interested to use the tooling you've set up but isn't quite sure where to get started (some typical commands for example) would be very helpful.

good call, will do.

[Steve Ognibene (nycdotnet)]

Thanks Ido David (@ido-namely) !

[James Craig Burley (jcburley)]

A lot of this LGTM, and the Renovate explanation helps give me some context, but I'm not yet enough of an expert to properly review all of this, so will (for now) just Comment.

Please let me know whether you want me to find some time to take a deeper dive in order to reach a go/no-go decision on this.

(Overall this seems like another great improvement to me.)