gopls/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: I117d8ae9ea605a4c78ee6a0816739e74b09b2e48
Reviewed-on: https://go-review.googlesource.com/c/tools/+/316449
Trust: Bryan C. Mills <bcmills@google.com>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
diff --git a/gopls/go.mod b/gopls/go.mod
index 2a5810e..6d16350 100644
--- a/gopls/go.mod
+++ b/gopls/go.mod
@@ -1,15 +1,20 @@
 module golang.org/x/tools/gopls
 
-go 1.16
+go 1.17
 
 require (
+	github.com/BurntSushi/toml v0.3.1 // indirect
 	github.com/google/go-cmp v0.5.5
+	github.com/google/safehtml v0.0.2 // indirect
 	github.com/jba/templatecheck v0.5.0
 	github.com/sanity-io/litter v1.5.0
 	github.com/sergi/go-diff v1.1.0
 	golang.org/x/mod v0.4.2
+	golang.org/x/sync v0.0.0-20210220032951-036812b2e83c // indirect
 	golang.org/x/sys v0.0.0-20210403161142-5e06dd20ab57
+	golang.org/x/text v0.3.3 // indirect
 	golang.org/x/tools v0.1.0
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
 	honnef.co/go/tools v0.1.3
 	mvdan.cc/gofumpt v0.1.1
 	mvdan.cc/xurls/v2 v2.2.0