Fail CI on first fail (as is default)

I had disabled this to figure out which platforms & versions are failing.
Now that that's done, no need to waste more cycles on that.

Author: black-puppydog

.github/workflows/main.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     strategy:
-      fail-fast: false
+      fail-fast: true
       matrix:
         os: [macos-latest, windows-latest, ubuntu-latest]
         node-version: [10.x, 12.x, 14.x]