devel/go-tools: update to 0.19.0

This will be the last version including the guru command.

Selected upstream changes:

• internal/versions: fix package to accept go1.21.0-bigcorp
• x/tools: don't parse CombinedOutput
• cmd/getgo: delete package
• cmd/deadcode: avoid ssautil.AllFunctions
• x/tools: update telemetry import (new Start API)
• x/tools: add explicit Unalias operations
• x/tools: drop go1.18 support
• cmd/callgraph: add 'posn' template helper

Changelog: https://github.com/golang/tools/compare/v0.18.0...v0.19.0