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: Iabb65fc3ed9727abecc3926abcecd445c967d0a9
Reviewed-on: https://go-review.googlesource.com/c/text/+/315571
Trust: Bryan C. Mills <[email protected]>
Run-TryBot: Bryan C. Mills <[email protected]>
TryBot-Result: Go Bot <[email protected]>
Reviewed-by: Alexander Rakoczy <[email protected]>
Reviewed-by: Marcel van Lohuizen <[email protected]>

go.mod

@@ -2,4 +2,4 @@ module github.com/xhit/text
 
 require golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e
 
-go 1.11
+go 1.17