Sort out some issues with our CI setup

* add missing apt-get update where needed
* move some jobs to run on ubuntu-20.04
* update actions plugins to latest
* speed up the job that runs multiplayer tests

.github/workflows/cpp_lint.yml

@@ -26,12 +26,13 @@ on:
 jobs:
 
 #  clang_format:
-#    runs-on: ubuntu-18.04
+#    runs-on: ubuntu-20.04
 #    steps:
-#      - uses: actions/checkout@v2
+#      - uses: actions/checkout@v3
 #      - name: Install clang-format
 #        run: |
-#          sudo apt-get install clang-format-9 -qyy
+#          sudo apt-get update
+#          sudo apt-get install -y clang-format-9
 #
 #      - name: Run clang-format
 #        run: |
@@ -41,14 +42,13 @@ jobs:
 #          CLANG_FORMAT: clang-format-9
 
   clang_tidy:
-    runs-on: ubuntu-18.04
+    runs-on: ubuntu-20.04
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
     - name: Install deps
       run: |
-        sudo apt-get install clang-tidy-9 -qyy
         source ./util/ci/common.sh
-        install_linux_deps
+        install_linux_deps clang-tidy-9
 
     - name: Run clang-tidy
       run: |