Bump unrolled/render to v1.1.0 (#15581)

v1.1.0 has improved buffer pooling

vendor/github.com/unrolled/render/genericbufferpool.go

@@ -0,0 +1,9 @@
+package render
+
+import "bytes"
+
+// GenericBufferPool abstracts buffer pool implementations
+type GenericBufferPool interface {
+	Get() *bytes.Buffer
+	Put(*bytes.Buffer)
+}