ci: Update to Swift 5.1

.swift-version

@@ -1 +1 @@
-5.0.2
+5.1

.travis.yml

@@ -30,12 +30,17 @@ matrix:
       dist: xenial
       sudo: required
       services: docker
-      env: DOCKER_IMAGE=swift:5.0.2-xenial
+      env: DOCKER_IMAGE=swift:5.0.3-xenial SWIFT_SNAPSHOT=5.0.3
     - os: linux
       dist: xenial
       sudo: required
       services: docker
-      env: DOCKER_IMAGE=swift:5.0.2 SWIFT_SNAPSHOT=$SWIFT_DEVELOPMENT_SNAPSHOT
+      env: DOCKER_IMAGE=swift:5.1
+    - os: linux
+      dist: xenial
+      sudo: required
+      services: docker
+      env: DOCKER_IMAGE=swift:5.1 SWIFT_SNAPSHOT=$SWIFT_DEVELOPMENT_SNAPSHOT
     - os: osx
       osx_image: xcode9.2
       sudo: required
@@ -52,6 +57,9 @@ matrix:
       osx_image: xcode10.2
       sudo: required
       env: SWIFT_SNAPSHOT=5.0.1 JAZZY_ELIGIBLE=true
+    - os: osx
+      osx_image: xcode11
+      sudo: required
     - os: osx
       osx_image: xcode11
       sudo: required