package.json: remove tslint

tslint is deprecated. We are using gts & eslint.

Change-Id: Icbbf1845044d54c6bb33fbd156c515ce292777a1
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/418546
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Peter Weinberger <[email protected]>

Author: hyangah