Updates GolangCI lint (#1823)

* changing plural to be singular on the modules variable

* Updates GolangCI lint 

It seems that GolangCI-lint has some issues with Go 1.13 mentioned [here](golangci/golangci-lint#659). This PR updates the version we're using.

* adding correct version to slim dockerfile

Dockerfile.build

@@ -26,7 +26,7 @@ RUN go get -tags sqlite -v -u github.com/gobuffalo/pop \
 && rm -rf $GOPATH/src && mkdir -p $BP
 
 # Install golangci
-RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.16.0
+RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.21.0
 
 WORKDIR $BP
 

Dockerfile.slim.build

@@ -24,7 +24,7 @@ RUN go get -u github.com/golang/dep/cmd/dep \
 && go get -v -u github.com/gorilla/sessions \
 && go get -v -u golang.org/x/vgo
 
-RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.16.0
+RUN curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin v1.21.0
 
 
 RUN npm i -g --no-progress yarn \