Eigentlich ganz einfach: Runterladen, entpacken und in /usr/local verschieben.
# download current version (1.13.3)
mkdir golang-update
cd golang-update
wget https://dl.google.com/go/go1.13.3.linux-amd64.tar.gz
tar xvzf go1.13.3.linux-amd64.tar.gz
# remove old version
sudo rm -rf /usr/local/go
# move new version in place
sudo mv go /usr/local
# set GOPATH and add folders to PATH
export GOPATH=$HOME/go
export PATH=$PATH:/usr/local/go/bin:$GOPATH/bin
# run go version
go version
# result: go version go1.13.3 linux/amd64