go.mod: upgrade to go 1.17

This change was produced using 'go mod tidy -go=1.17'
with a go command built at CL 315210.

This activates lazy loading, and updates the go.mod file to maintain
the lazy-loading invariants (namely, including an explicit requirement
for every package transitively imported by the main module).

Note that this does *not* prevent users with earlier go versions from
successfully building packages from this module.

For golang/go#36460.

Change-Id: Iad25619ccbce82b91bbf51d13a79404c6e998dcc
Reviewed-on: https://go-review.googlesource.com/c/term/+/316112
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

go.mod

@@ -1,5 +1,5 @@
 module golang.org/x/term
 
-go 1.11
+go 1.17
 
 require golang.org/x/sys v0.0.0-20201119102817-f84b799fce68