update ci matrix

Author: abhinavsns

.github/workflows/UnitTests.yml

@@ -13,21 +13,29 @@ jobs:
       fail-fast: false
       matrix:
         julia-version:
-          - '1.0'
-          - '1.5'
-          - '1.6' # LTS
-          - '1'
-        julia-arch: [x64, x86]
-        os: [ubuntu-latest, windows-latest, macOS-latest]
-        exclude:
-          - os: macOS-latest
-            julia-arch: x86
-        experimental: [false]
-        include:
-          - julia-version: nightly
-            julia-arch: x64
-            os: ubuntu-latest
-            experimental: true
+            - '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
+              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