Remove Buf dependency references

buf.lock already locks us to specific dependency versions, and we want
to receive updates to later ones, so it makes the most sense to not pin
to specific tags.

This change also aligns with Buf's recommendations at
https://buf.build/docs/configuration/v2/buf-yaml/#deps.

Author: lberrymage

buf.yaml

@@ -7,8 +7,8 @@ modules:
   - path: .
     name: buf.build/accrescent/appstore-api
 deps:
-  - buf.build/accrescent/android-bundle:v1.1.0
-  - buf.build/bufbuild/protovalidate:v1.1.0
+  - buf.build/accrescent/android-bundle
+  - buf.build/bufbuild/protovalidate
 lint:
   use:
     - STANDARD