Update golangci

@StevenACoffman pointed out in #241
that the 1.27 release has CPU and memory usage improvements - since
we've struggled with CPU limitations in the past, and had linting
timeout as a result, seems worth an upgrade!

tekton/images/test-runner/Dockerfile

@@ -168,7 +168,7 @@ RUN go get -u github.com/google/ko/cmd/ko && \
     GO111MODULE="on" go get -u github.com/raviqqe/liche
 
 # Install GolangCI linter: https://github.com/golangci/golangci-lint/
-ARG GOLANGCI_VERSION=1.26.0
+ARG GOLANGCI_VERSION=1.27.0
 RUN curl -sL https://github.com/golangci/golangci-lint/releases/download/v${GOLANGCI_VERSION}/golangci-lint-${GOLANGCI_VERSION}-linux-amd64.tar.gz | tar -C /usr/local/bin -xvzf - --strip-components=1 --wildcards "*/golangci-lint"
 
 # Install Kustomize: