[release] extension/LICENSE: update license

We didn't update the release branch's LICENSE file during the
v0.41.0 release.
CL 551115 replaced `web-request` with `node-fetch`
and that changed indirect dependencies a lot.

Regenerated the license file by running

  cd extension && ./tools/license.sh && mv LICENSE.prod LICENSE

For #3453

Change-Id: I0f5a34c380ae8c717e86979d368ec291cc575b74
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/598458
kokoro-CI: kokoro <noreply+kokoro@google.com>
Commit-Queue: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>