Update .tool-versions to Go 1.18.7

stanhu · stanhu · commit afc26e3deac1 · 2022-10-12T12:24:13.000-07:00
Security announcement: https://groups.google.com/g/golang-announce/c/xtuG5faxtaU Part of https://gitlab.com/groups/gitlab-org/-/epics/8843
diff --git a/.tool-versions b/.tool-versions
@@ -1,2 +1,2 @@
 ruby 2.7.5
-golang 1.18.6
+golang 1.18.7
