Update ci.yml

Author: pdimov

.github/workflows/ci.yml

@@ -19,11 +19,13 @@ jobs:
         include:
           - toolset: gcc-5
             cxxstd: "03,11,14,1z"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
             install: g++-5
           - toolset: gcc-6
             cxxstd: "03,11,14,1z"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
             install: g++-6
           - toolset: gcc-7
             cxxstd: "03,11,14,17"
@@ -51,27 +53,30 @@ jobs:
           - toolset: clang
             compiler: clang++-3.9
             cxxstd: "03,11,14"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
             install: clang-3.9
           - toolset: clang
             compiler: clang++-4.0
             cxxstd: "03,11,14"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
             install: clang-4.0
           - toolset: clang
             compiler: clang++-5.0
             cxxstd: "03,11,14,1z"
-            os: ubuntu-18.04
+            os: ubuntu-latest
+            container: ubuntu:18.04
             install: clang-5.0
           - toolset: clang
             compiler: clang++-6.0
             cxxstd: "03,11,14,17"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
             install: clang-6.0
           - toolset: clang
             compiler: clang++-7
             cxxstd: "03,11,14,17"
-            os: ubuntu-18.04
+            os: ubuntu-20.04
             install: clang-7
           - toolset: clang
             compiler: clang++-8
@@ -108,15 +113,29 @@ jobs:
           - toolset: clang
             cxxstd: "03,11,14,17,2a"
             os: macos-11
+          - toolset: clang
+            cxxstd: "03,11,14,17,20,2b"
+            os: macos-12
 
     runs-on: ${{matrix.os}}
+    container: ${{matrix.container}}
+
+    defaults:
+      run:
+        shell: bash
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
+
+      - name: Setup container environment
+        if: matrix.container
+        run: |
+          apt-get update
+          apt-get -y install sudo python git g++
 
       - name: Install packages
         if: matrix.install
-        run: sudo apt install ${{matrix.install}}
+        run: sudo apt-get -y install ${{matrix.install}}
 
       - name: Setup Boost
         run: |
@@ -179,7 +198,7 @@ jobs:
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Setup Boost
         shell: cmd
@@ -214,15 +233,15 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-18.04
           - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: macos-11
+          - os: macos-12
 
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install packages
         if: matrix.install
@@ -261,15 +280,15 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-18.04
           - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: macos-11
+          - os: macos-12
 
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install packages
         if: matrix.install
@@ -318,15 +337,15 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - os: ubuntu-18.04
           - os: ubuntu-20.04
           - os: ubuntu-22.04
           - os: macos-11
+          - os: macos-12
 
     runs-on: ${{matrix.os}}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - name: Install packages
         if: matrix.install