Upgrade to Go 1.17, protobuf v1.26.0, etc

What's Changed

• add stitch proto by Mike Hamrah (@mhamrah) in #1
• Upgrade to Go 1.17, protobuf v1.26.0 by James Craig Burley (@jcburley) in #2

New Contributors

• Mike Hamrah (@mhamrah) made their first contribution in #1
• James Craig Burley (@jcburley) made their first contribution in #2

Full Changelog: https://github.com/namely/giraffe-proto/commits/v0.1.0