Update swift-tools-version to 5.2.

Author: paulofaria

.swift-version

@@ -1 +1 @@
-5.1
+5.2

.travis.yml

@@ -1,25 +1,19 @@
-notifications:
-  slack: zewo:VjyVCCQvTOw9yrbzQysZezD1
 language: generic
 env:
   global:
-  - SWIFT_VERSION=5.1
+  - SWIFT_VERSION=5.2
 matrix:
   include:
     - os: osx
       env: JOB=SwiftPM_OSX
       osx_image: xcode11
     - os: linux
       env: JOB=SwiftPM_linux
-      dist: bionic
+      dist: focal
       sudo: required
       install:
         -  travis_retry eval "$(curl -sL https://gist.githubusercontent.com/kylef/5c0475ff02b7c7671d2a/raw/9f442512a46d7a2af7b850d65a7e9bd31edfb09b/swiftenv-install.sh)"
 script:
   - swift build -c release
   - swift build
   - swift test --enable-test-discovery
-  - 'if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then
-       eval "$(curl -sL https://raw.githubusercontent.com/lgaches/swifttravisci/master/codecov)";
-     fi'
-

Package.swift

@@ -1,4 +1,4 @@
-// swift-tools-version:5.1
+// swift-tools-version:5.2
 import PackageDescription
 
 let package = Package(

README.md

@@ -6,7 +6,6 @@ The Swift implementation for GraphQL, a query language for APIs created by Faceb
 [![License][mit-badge]][mit-url]
 [![Slack][slack-badge]][slack-url]
 [![Travis][travis-badge]][travis-url]
-[![Codecov][codecov-badge]][codecov-url]
 [![Codebeat][codebeat-badge]][codebeat-url]
 
 Looking for help? Find resources [from the community](http://graphql.org/community/).
@@ -22,16 +21,13 @@ This repo only contains the core GraphQL implementation. For a better experience
 
 This project is released under the MIT license. See [LICENSE](LICENSE) for details.
 
-[swift-badge]: https://img.shields.io/badge/Swift-5.1-orange.svg?style=flat
+[swift-badge]: https://img.shields.io/badge/Swift-5.2-orange.svg?style=flat
 [swift-url]: https://swift.org
 [mit-badge]: https://img.shields.io/badge/License-MIT-blue.svg?style=flat
 [mit-url]: https://tldrlegal.com/license/mit-license
-[slack-image]: http://s13.postimg.org/ybwy92ktf/Slack.png
-[slack-badge]: https://zewo-slackin.herokuapp.com/badge.svg
+[slack-badge]: http://slack.zewo.io/badge.svg
 [slack-url]: http://slack.zewo.io
 [travis-badge]: https://travis-ci.org/GraphQLSwift/GraphQL.svg?branch=master
 [travis-url]: https://travis-ci.org/GraphQLSwift/GraphQL
-[codecov-badge]: https://codecov.io/gh/GraphQLSwift/GraphQL/branch/master/graph/badge.svg
-[codecov-url]: https://codecov.io/gh/GraphQLSwift/GraphQL
 [codebeat-badge]: https://codebeat.co/badges/13293962-d1d8-4906-8e62-30a2cbb66b38
 [codebeat-url]: https://codebeat.co/projects/github-com-graphqlswift-graphql