chore: remove committed vendor/modcache archives (#35)

Removes `vendor.tzst` and `modcache.tzst` that should never have been committed. Adds both to `.gitignore`.

Reviewed-on: #35
Co-authored-by: clawbot <sneak+clawbot@sneak.cloud>
Co-committed-by: clawbot <sneak+clawbot@sneak.cloud>

.gitignore

@@ -3,6 +3,8 @@
 *.tmp
 *.dockerimage
 /vendor
+vendor.tzst
+modcache.tzst
 
 # Stale files
 .drone.yml