bump go-ctags for handling non-fatal startup errors (#972)
Currently if you switch to universal-ctags 6.2.0 it will log a few
warnings on startup. The old version of go-ctags would error out. Now
instead it will log to its info log.
Test Plan: Added the problematic file in the linked issue to ./foo/repo
directory. Then ran "go run ./cmd/zoekt-index -require_ctags -index
./foo/index ./foo/repo" with uctags 6.2.0.