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-bionic/Dockerfile b/build/docker/ubuntu-bionic/Dockerfile
index e69df5a..134d3ef 100644
--- a/build/docker/ubuntu-bionic/Dockerfile
+++ b/build/docker/ubuntu-bionic/Dockerfile
@@ -132,9 +132,9 @@
libglib2.0-dev
# golang
-ENV GOLANG_VERSION 1.17.6
+ENV GOLANG_VERSION 1.18.1
ENV GOLANG_DOWNLOAD_URL https://go.dev/dl/go$GOLANG_VERSION.linux-amd64.tar.gz
-ENV GOLANG_DOWNLOAD_SHA256 231654bbf2dab3d86c1619ce799e77b03d96f9b50770297c8f4dff8836fc8ca2
+ENV GOLANG_DOWNLOAD_SHA256 b3b815f47ababac13810fc6021eb73d65478e0b2db4b09d348eefad9581a2334
RUN curl -fsSL "$GOLANG_DOWNLOAD_URL" -o golang.tar.gz && \
echo "$GOLANG_DOWNLOAD_SHA256 golang.tar.gz" | sha256sum -c - && \
tar -C /usr/local -xzf golang.tar.gz && \