use go install instead of go get in /contrib/raftexample/Procfile

[wathenjiang]

What happened?

The go version of etcd is go 1.17 right now.

Please see golang/go#40276

With this change, go install would overlap with go get even more, so we also
propose deprecating and removing the ability for go get to install packages.

In Go 1.16, when go get is invoked outside a module or when go get is
invoked without the -d flag with arguments matching one or more main
packages, go get would print a deprecation warning recommending an
equivalent go install command.
In a later release (likely Go 1.17), go get would no longer build or install
packages. The -d flag would be enabled by default. Setting -d=false would
be an error. If go get is invoked outside a module, it would print an error
recommending an equivalent go install command.

If you run go get github.com/mattn/goreman in go1.17(or later), it will not build or install packages.

By go get, if you run the following command, you will get the following error:

$ ./goreman start
command not found: goreman

What did you expect to happen?

Use go install github.com/mattn/goreman@latest instead.

How can we reproduce it (as minimally and precisely as possible)?

none.

Anything else we need to know?

No response

Etcd version (please run commands below)

none.

Etcd configuration (command line flags or environment variables)

paste your configuration here

Etcd debug information (please run commands blow, feel free to obfuscate the IP address or FQDN in the output)

$ etcdctl member list -w table
# paste output here

$ etcdctl --endpoints=<member list> endpoint status -w table
# paste output here

Relevant log output

No response

[ahrtr]

The PR 14060 has already been merged, so closing this ticket.