CI update and remove swift 4.x support (#82)

* Remove Swift 4.x support; Update TravisCI

* Update SPM syntax and minimum version dependency on swift-log

.travis.yml

@@ -15,55 +15,28 @@ matrix:
       dist: xenial
       sudo: required
       services: docker
-      env:  DOCKER_IMAGE=swift:4.0.3 SWIFT_SNAPSHOT=4.0.3
+      env: DOCKER_IMAGE=docker.kitura.net/kitura/swift-ci-ubuntu16.04:5.1.5
     - os: linux
-      dist: xenial
-      sudo: required
-      services: docker
-      env: DOCKER_IMAGE=swift:4.1.3 SWIFT_SNAPSHOT=4.1.3
-    - os: linux
-      dist: xenial
-      sudo: required
-      services: docker
-      env: DOCKER_IMAGE=swift:4.2.4 SWIFT_SNAPSHOT=4.2.4
-    - os: linux
-      dist: xenial
-      sudo: required
-      services: docker
-      env: DOCKER_IMAGE=swift:5.0.3-xenial SWIFT_SNAPSHOT=5.0.3
-    - os: linux
-      dist: xenial
+      dist: bionic
       sudo: required
       services: docker
-      env: DOCKER_IMAGE=swift:5.1
+      env: DOCKER_IMAGE=docker.kitura.net/kitura/swift-ci-ubuntu18.04:5.4
     - os: linux
       dist: xenial
       sudo: required
       services: docker
-      env: DOCKER_IMAGE=swift:5.1 SWIFT_SNAPSHOT=$SWIFT_DEVELOPMENT_SNAPSHOT
-    - os: osx
-      osx_image: xcode9.2
-      sudo: required
-      env: SWIFT_SNAPSHOT=4.0.3
-    - os: osx
-      osx_image: xcode9.4
-      sudo: required
-      env: SWIFT_SNAPSHOT=4.1.2
+      env: DOCKER_IMAGE=docker.kitura.net/kitura/swift-ci-ubuntu18.04:latest USE_SWIFT_DEVELOPMENT_SNAPSHOT=1
     - os: osx
-      osx_image: xcode10.1
+      osx_image: xcode11
       sudo: required
-      env: SWIFT_SNAPSHOT=4.2.1
+      env: SWIFT_SNAPSHOT=5.1.5 JAZZY_ELIGIBLE=true
     - os: osx
-      osx_image: xcode10.2
+      osx_image: xcode12.2
       sudo: required
-      env: SWIFT_SNAPSHOT=5.0.1 JAZZY_ELIGIBLE=true
     - os: osx
-      osx_image: xcode11
-      sudo: required
-    - os: osx
-      osx_image: xcode11
+      osx_image: xcode12.5
       sudo: required
-      env: SWIFT_SNAPSHOT=$SWIFT_DEVELOPMENT_SNAPSHOT
+      env: USE_SWIFT_DEVELOPMENT_SNAPSHOT=1
 
 before_install:
   - git clone https://github.com/Kitura/Package-Builder.git

Package.swift

@@ -29,10 +29,8 @@ let package = Package(
         )
     ],
     dependencies: [
-        // Note: Syntax to allow compatibility with both Swift 4 and Swift 5 projects.
-        // See: https://github.com/apple/swift-log#help-i-need-swift-4
-        .package(url: "https://github.com/apple/swift-log.git", Version("0.0.0") ..< Version("2.0.0")),
-        .package(url: "https://github.com/Kitura/LoggerAPI.git", from: "1.9.200")
+        .package(url: "https://github.com/apple/swift-log.git", from: "1.0.0"),
+        .package(url: "https://github.com/Kitura/LoggerAPI.git", from: "2.0.0"),
     ],
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.