ci: standardise the tests workflow, using the reusable workflow

* Standardise the tests workflow, using the reusab SciML tests workflow.
* Rename the tests workflow to `Tests.yml`, instead of `CI.yml`, since
it's more semantically correct and CI encompasses all the workflows that
are run.

Author: thazhemadam

.github/workflows/CI.yml

@@ -0,0 +1,27 @@
+name: "Run Tests"
+
+on:
+  push:
+    branches:
+      - 'master'
+  pull_request:
+    branches:
+      - 'master'
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref_name != github.event.repository.default_branch || github.ref != 'refs/tags/v*' }}
+
+jobs:
+  tests:
+    name: "Tests"
+    strategy:
+      fail-fast: false
+      matrix:
+        group:
+          - Core
+    uses: "SciML/.github/.github/workflows/tests.yml@v1"
+    with:
+      group: ${{ matrix.group }}
+      julia-version: '1'
+    secrets: "inherit"