bump golang to 1.14

.travis.yml

@@ -1,7 +1,7 @@
 language: go
 
 go:
-  - 1.13.x
+  - 1.14.x
 services:
   - docker
 script:

Dockerfile.npc

@@ -1,4 +1,4 @@
-FROM golang:1.13 as builder
+FROM golang:1.14 as builder
 ARG GOPROXY=direct
 WORKDIR /go/src/ehang.io/nps
 COPY . .

Dockerfile.nps

@@ -1,4 +1,4 @@
-FROM golang:1.13 as builder
+FROM golang:1.14 as builder
 ARG GOPROXY=direct
 WORKDIR /go/src/ehang.io/nps
 COPY . .

go.mod

@@ -1,6 +1,6 @@
 module ehang.io/nps
 
-go 1.13
+go 1.14
 
 require (
 	ehang.io/nps-mux v0.0.0-20200617154922-5dc86cc6082a