update ci matrix

Author: abhinavsns

.github/workflows/UnitTests.yml

@@ -11,21 +11,30 @@ jobs:
     continue-on-error: ${{ matrix.julia-version == 'nightly' }}
     strategy:
       fail-fast: false
-      matrix:
-        julia-version:
-          - '1.6' # LTS
-          - '1.10'
-        julia-arch: [x64, x86, arm64]
-        os: [ubuntu-latest, windows-latest, macOS-latest]
-        exclude:
-          - os: macOS-latest
-            julia-arch: [x64, x86]
+      julia-version:
+          - '1'
+        os: [ubuntu-latest, macOS-latest, windows-latest]
         experimental: [false]
         include:
+          # Include nightly, but experimental, so it's allowed to fail without
+          # failing CI.
           - julia-version: nightly
-            julia-arch: x64
             os: ubuntu-latest
             experimental: true
+            fail_ci_if_error: false
+          # Windows is extremely slow on 1.6, so we skip this combination,
+          # since it increases CI time by 5x
+          - julia-version: '1.7'
+            os: windows-latest
+            experimental: false
+          # Oldest supported version
+          - julia-version: '1.6'
+            os: ubuntu-latest
+            experimental: false
+          # MacOS Aarch64 reached Tier1 support of Julia in version 1.9
+          - julia-version: '1.9'
+            os: macOS-latest
+            experimental: false
 
     steps:
       - name: Checkout Repository