chore(repo): update ci workflow post-stencil v4 (#355)

this commit updates the stencil version matrix in the main ci workflow
to:
- no longer use "latest" and "v4-next", now that stencil v4 is out
- explicitly run with stencil v3, v4

as a result, we should expect four runs of this workflow to run in
parallel - one for stencil v2, v3, & v4, as well as  one for the version
of stencil that is installed in package-lock.json. there is expected to
be some overlap between the latest two major versions and "latest" (the
latter will point to either v3 or v4, depending on the state of the
repo)

.github/workflows/main.yml

@@ -13,17 +13,16 @@ jobs:
     name: (stencil-sass with Stencil version ${{ matrix.stencil_version }})
     strategy:
       matrix:
-        # Run two different versions in parallel:
+        # Run with multiple different versions of Stencil in parallel:
         # 1. DEFAULT - uses the version of Stencil written in `package-lock.json`, keeping the same version used by the
         # Stencil team as a source of truth
         # 2. 2 - will install the latest release under major version 2 of Stencil. This should be kept as long as this
         # library supports Stencil v2.Y.Z
-        # 3. v4-next - will install a pre-release version of Stencil v4, and is used to detect any regressions in a
-        # pre-release of v4.0.0.
-        # 4. latest - will install the latest version of Stencil. Prior to the Stencil v4.0.0 release, this will
-        # resolve to the latest version of Stencil v3. After the Stencil v4.0.0 release, it will resolve to the latest
-        # version of Stencil v4.
-        stencil_version: ['DEFAULT', '2', 'v4-next', 'latest']
+        # 3. 3 - will install the latest release under major version 3 of Stencil. This should be kept as long as this
+        # library supports Stencil v3.Y.Z
+        # 4. 4 - will install the latest release under major version 4 of Stencil. This should be kept as long as this
+        # library supports Stencil v4.Y.Z
+        stencil_version: ['DEFAULT', '2', '3', '4']
     runs-on: ubuntu-latest
 
     steps: