github/workflows: fix the syntax error in ci.yml

Fixes the error in https://github.com/golang/vscode-go/actions/runs/53803644

And triggers the workflow for all push/prs.

Change-Id: I1aa506b0863485a640b47c5da1993ace739c4ce8
GitHub-Last-Rev: dac3185
GitHub-Pull-Request: #7
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/222924
Reviewed-by: Hyang-Ah Hana Kim <[email protected]>

Author: hyangah

.github/workflows/ci.yml

@@ -1,14 +1,6 @@
 name: build
 
-on:
-  # Trigger the workflow on push or pull request,
-  # but only for the master branch
-  push:
-    branches:
-      - *
-  pull_request:
-    branches:
-      - master
+on: [push, pull_request]
 
 env:
   GOPATH: /tmp/go