Fix installation of golangci-lint on devcontainer

Prior to this commit, vscode was saying "Analysis tools missing" and
prompting to install it.
Fix was to install golangci-lint via go get, as per:
golangci/golangci-lint#1037 (comment)

Author: johnboyes

.devcontainer/Dockerfile

@@ -39,6 +39,7 @@ RUN apt-get update \
         github.com/fatih/gomodifytags@latest  \
         github.com/mgechev/revive@latest  \
         github.com/go-delve/delve/cmd/dlv@latest 2>&1 \
+        github.com/golangci/golangci-lint/cmd/[email protected] \
     #
     # Build gocode-gomod
     && GOPATH=/tmp/gotools go get -x -d github.com/stamblerre/gocode 2>&1 \
@@ -48,9 +49,6 @@ RUN apt-get update \
     && mv /tmp/gotools/bin/* /usr/local/bin/ \
     && mv gocode-gomod /usr/local/bin/ \
     #
-    # Install golangci-lint
-    && curl -sSfL https://raw.githubusercontent.com/golangci/golangci-lint/master/install.sh | sh -s -- -b /usr/local/bin 2>&1 \
-    #
     # Create a non-root user to use if preferred - see https://aka.ms/vscode-remote/containers/non-root-user.
     && groupadd --gid $USER_GID $USERNAME \
     && useradd -s /bin/bash --uid $USER_UID --gid $USER_GID -m $USERNAME \