Update yarn version in CI, resolve dependency conflict

.travis.yml

@@ -4,6 +4,8 @@ node_js:
 os:
   - linux
 dist: trusty
+before_install:
+  - npm install -g yarn@1.17.3
 install:
   - yarn install --frozen-lockfile
 script:

appveyor.yml

@@ -9,6 +9,7 @@ install:
   - systeminfo | findstr /C:"OS"
   - set PATH=C:\Ruby23-x64\bin;%PATH%
   - ps: Install-Product node 10.13.0 x64
+  - ps: .\build\install-yarn.ps1
   - yarn install --frozen-lockfile
 
 build_script:

build/install-yarn.ps1

@@ -0,0 +1,12 @@
+# via https://gist.github.com/FeodorFitsner/1056703ec92bd6a3012c15fe78a5e162
+
+Write-Host "Installing Yarn..." -ForegroundColor Cyan
+
+Write-Host "Downloading..."
+$msiPath = "$env:TEMP\yarn.msi"
+(New-Object Net.WebClient).DownloadFile('https://github.com/yarnpkg/yarn/releases/download/v1.17.3/yarn-1.17.3.msi', $msiPath)
+
+Write-Host "Installing..."
+cmd /c start /wait msiexec /i "$msiPath" /quiet
+
+Write-Host "Yarn installed" -ForegroundColor Green

package.json

@@ -112,6 +112,9 @@
     "uuid": "3.3.2",
     "websocket": "1.0.28"
   },
+  "resolutions": {
+    "fbjs/isomorphic-fetch/node-fetch": "https://github.com/scottnonnenberg-signal/node-fetch.git#3e5f51e08c647ee5f20c43b15cf2d352d61c36b4"
+  },
   "devDependencies": {
     "@types/chai": "4.1.2",
     "@types/classnames": "2.2.3",

yarn.lock

@@ -6282,6 +6282,7 @@ node-dir@^0.1.10:
 
 node-fetch@^1.0.1, "node-fetch@https://github.com/scottnonnenberg-signal/node-fetch.git#3e5f51e08c647ee5f20c43b15cf2d352d61c36b4":
   version "1.7.3"
+  uid "3e5f51e08c647ee5f20c43b15cf2d352d61c36b4"
   resolved "https://github.com/scottnonnenberg-signal/node-fetch.git#3e5f51e08c647ee5f20c43b15cf2d352d61c36b4"
   dependencies:
     encoding "^0.1.11"