Update Go versions used in travis and LANGUAGES.md
Per our support policy, drop support of go 1.16 and add support of go
1.18.
Also enable go vet in make check, and fix issues reported by go vet.
diff --git a/build/docker/ubuntu-xenial/Dockerfile b/build/docker/ubuntu-xenial/Dockerfile
index 7f856ff..637fa25 100644
--- a/build/docker/ubuntu-xenial/Dockerfile
+++ b/build/docker/ubuntu-xenial/Dockerfile
@@ -136,9 +136,9 @@
libglib2.0-dev
# golang
-ENV GOLANG_VERSION 1.16.13
+ENV GOLANG_VERSION 1.17.9
ENV GOLANG_DOWNLOAD_URL https://go.dev/dl/go$GOLANG_VERSION.linux-amd64.tar.gz
-ENV GOLANG_DOWNLOAD_SHA256 275fc03c90c13b0bbff13125a43f1f7a9f9c00a0d5a9f2d5b16dbc2fa2c6e12a
+ENV GOLANG_DOWNLOAD_SHA256 9dacf782028fdfc79120576c872dee488b81257b1c48e9032d122cfdb379cca6
RUN curl -fsSL "$GOLANG_DOWNLOAD_URL" -o golang.tar.gz && \
echo "$GOLANG_DOWNLOAD_SHA256 golang.tar.gz" | sha256sum -c - && \
tar -C /usr/local -xzf golang.tar.gz && \