Use go mod download to install deps on travis-ci. Add cache for travis-ci.

Signed-off-by: Artemiy Ryabinkov <getlag@ya.ru>

.travis.yml

@@ -4,6 +4,9 @@ go:
   - 1.x
   - tip
 
+git:
+  depth: 1
+
 # Derived from https://github.com/lib/pq/blob/master/.travis.yml
 before_install:
   - ./travis/before_install.bash
@@ -12,6 +15,7 @@ env:
   global:
     - GO111MODULE=on
     - GOPROXY=https://proxy.golang.org
+    - GOFLAGS=-mod=readonly
     - PGX_TEST_CONN_STRING=postgres://pgx_md5:secret@127.0.0.1/pgx_test
     - PGX_TEST_UNIX_SOCKET_CONN_STRING="host=/var/run/postgresql database=pgx_test"
     - PGX_TEST_TCP_CONN_STRING=postgres://pgx_md5:secret@127.0.0.1/pgx_test
@@ -26,11 +30,15 @@ env:
     - PGVERSION=9.4
     - PGVERSION=9.3
 
+cache:
+  directories:
+    - $HOME/.cache/go-build
+    - $HOME/gopath/pkg/mod
+
 before_script:
   - ./travis/before_script.bash
 
-install:
-  - ./travis/install.bash
+install: go mod download
 
 script:
   - ./travis/script.bash

travis/install.bash

@@ -1,14 +0,0 @@
-#!/usr/bin/env bash
-set -eux
-
-go get -u github.com/cockroachdb/apd
-go get -u github.com/shopspring/decimal
-go get -u gopkg.in/inconshreveable/log15.v2
-go get -u github.com/jackc/fake
-go get -u github.com/lib/pq
-go get -u github.com/hashicorp/go-version
-go get -u github.com/satori/go.uuid
-go get -u github.com/sirupsen/logrus
-go get -u github.com/pkg/errors
-go get -u go.uber.org/zap
-go get -u github.com/rs/zerolog