Identify runner OS with runner.os instead of matrix.os

.github/workflows/ci.yml

@@ -63,7 +63,7 @@ jobs:
     - uses: actions/checkout@v3
 
     - name: Cache the vcpkg archives
-      if: matrix.os != 'ubuntu-latest'
+      if: matrix.cache != ''
       uses: actions/cache@v3
       with:
         path: ${{matrix.cache}}
@@ -79,11 +79,11 @@ jobs:
         arch: ${{matrix.arch}}
 
     - name: Install apt dependencies (Linux)
-      if: matrix.os == 'ubuntu-latest'
+      if: runner.os == 'Linux'
       run: sudo apt-get install -y libssl-dev libcurl4-openssl-dev faketime
 
     - name: Setup the oldest supported version of cmake (macOS)
-      if: matrix.os == 'macOS-latest'
+      if: runner.os == 'macOS'
       uses: jwlawson/actions-setup-cmake@v1.12
       with:
         cmake-version: '3.17.0'
@@ -103,11 +103,11 @@ jobs:
         --config ${{env.BUILD_TYPE}}
 
     - name: List files (Linux/macOS)
-      if: matrix.os != 'windows-latest'
+      if: runner.os != 'Windows'
       run: find .. -ls
 
     - name: List files (Windows)
-      if: matrix.os == 'windows-latest'
+      if: runner.os == 'Windows'
       run: Get-ChildItem -Recurse -Name ..
 
     - name: Test