Update CI to Go 1.15

.github/workflows/test.yml

@@ -11,7 +11,7 @@ jobs:
     - uses: actions/checkout@main
     - uses: actions/setup-go@main
       with:
-        go-version: '1.13'
+        go-version: '1.15'
     - name: Run gofmt
       run: test -z $(gofmt -l .) || (gofmt -d . && exit 1)
 
@@ -23,11 +23,11 @@ jobs:
       - uses: actions/checkout@main
       - uses: actions/setup-go@main
         with:
-          go-version: '1.13'
+          go-version: '1.15'
       - name: Run golangci-lint
         run: |
-          curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s v1.22.2
-          ./bin/golangci-lint run -v ./...
+          curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b $(go env GOPATH)/bin v1.35.2
+          golangci-lint run -v ./...
 
   test:
     name: Test (go test)
@@ -37,7 +37,7 @@ jobs:
     - uses: actions/checkout@main
     - uses: actions/setup-go@main
       with:
-        go-version: '1.13'
+        go-version: '1.15'
     - name: Run go test
       run: go test -race -coverprofile=coverage.txt ./...
     - name: Upload coverage to codecov.io
@@ -56,7 +56,7 @@ jobs:
     - uses: actions/checkout@main
     - uses: actions/setup-go@main
       with:
-        go-version: '1.13'
+        go-version: '1.15'
     - name: Run go build
       run: |
         go build ./cli/battlesnake