Update dependencies

Among others, this updates minio-go, so that the new "eu-west-3" zone
for AWS is supported.

vendor/cloud.google.com/go/firestore/testdata/Makefile

@@ -0,0 +1,11 @@
+# Copy textproto files in this directory from the source of truth.
+
+SRC=$(GOPATH)/src/github.com/GoogleCloudPlatform/google-cloud-common/testing/firestore/testdata
+
+.PHONY: refresh
+
+refresh:
+	-rm *.textproto
+	cp $(SRC)/*.textproto .
+	openssl dgst -sha1 $(SRC)/tests.binprotos > VERSION
+