Remove support for network override in bake

Signed-off-by: Zachary Povey <zachary.povey@autotrader.co.uk>

bake/bake.go

@@ -567,8 +567,6 @@ func (t *Target) AddOverrides(overrides map[string]Override) error {
 					}
 				}
 			}
-		case "network":
-			t.NetworkMode = &o.Value
 		default:
 			return errors.Errorf("unknown key: %s", keys[0])
 		}

docs/reference/buildx_bake.md

@@ -291,7 +291,7 @@ $ docker buildx bake --set foo*.no-cache              # bypass caching only for
 
 Complete list of overridable fields:
 `args`, `cache-from`, `cache-to`, `context`, `dockerfile`, `labels`, `no-cache`,
-`output`, `platform`, `pull`, `secrets`, `ssh`, `tags`, `target`, `network`
+`output`, `platform`, `pull`, `secrets`, `ssh`, `tags`, `target`
 
 ### File definition