Use resolver instead yaml files to download ghc

Author: jneira

.azure/windows-cabal.yml

@@ -106,8 +106,8 @@ jobs:
   - bash: |
       source .azure/windows-cabal.bashrc
       # Needed for wrapper-test
-      stack setup --stack-yaml stack-8.8.1.yaml
-      stack setup --stack-yaml stack-8.6.5.yaml
+      stack setup --resolver ghc-8.8.1
+      stack setup --resolver ghc-8.6.5
       # TODO Enable :dispatcher-test suite
       cabal v2-test :plugin-dispatcher-test :wrapper-test # :dispatcher-test --project-file $PROJECT_FILE
     displayName: "Run Test: dispatcher-test, plugin-dispatcher-test and wrapper-test"

.azure/windows-stack.yml

@@ -119,8 +119,8 @@ jobs:
   - bash: |
       source .azure/windows-stack.bashrc
       # Needed for wrapper-test
-      stack setup --stack-yaml stack-8.8.1.yaml
-      stack setup --stack-yaml stack-8.6.5.yaml
+      stack setup --resolver ghc-8.8.1
+      stack setup --resolver ghc-8.6.5
       # TODO: Enable :dispatcher-test suite
       stack test :plugin-dispatcher-test :wrapper-test --stack-yaml $(YAML_FILE)
     displayName: "Run Test: dispatcher-test, plugin-dispatcher-test and wrapper-test"