Use apt-spy2 to fix spurious failures on GitHub (ad-freiburg#981)

On GitHub actions, Ubuntu's `apt` command is by default configured to always use the Ubuntu mirrors from Microsoft Azure for package installations and update . Every now and then these servers are unreachable or out of sync. During these periods all Ubuntu-based workflows fail, which is rather annoying.
This commit uses `apt-spy2` to first find reachable Ubuntu servers and only then runs `apt update && apt install ...`. This should reduce the probability of spurious check failures dramatically.

This commit also updates `absl` to the current (at the time of the commit) master.

.github/workflows/code-coverage.yml

@@ -37,18 +37,6 @@ jobs:
       with:
         submodules: "recursive"
 
-    - name: Install dependencies
-      run:  sudo apt update && sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
-    - name: Python dependencies
-      run: sudo apt-get install python3-yaml unzip pkg-config python3-icu python3-pip
-    - name: Create build directory
-      run: mkdir ${{github.workspace}}/build
-    - name: Install and run conan
-      working-directory: ${{github.workspace}}/build
-      run: >
-        sudo pip3 install "conan==1.58.0";
-        conan --version;
-        conan install .. -pr:h ../conanprofiles/clang-libcpp -pr:b ../conanprofiles/clang-libcpp;
     - name: Install clang 16
       # The sed command fixes a bug in `llvm.sh` in combination with the latest version of
       # `apt-key`. Without it the GPG key for the llvm repository is downloaded but deleted
@@ -60,6 +48,21 @@ jobs:
         sudo ./llvm.sh 15 
         sudo apt install clang-15 llvm-15
         sudo ./llvm.sh 16 all
+    - name: Install dependencies
+      run:  |
+        sudo gem install apt-spy2
+        sudo apt-spy2 fix --commit --launchpad --country=US
+        sudo apt-get update
+        sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
+    - name: Python dependencies
+      run: sudo apt-get install python3-yaml unzip pkg-config python3-icu python3-pip
+    - name: Create build directory
+      run: mkdir ${{github.workspace}}/build
+    - name: Install and run conan
+      working-directory: ${{github.workspace}}/build
+      run: >
+        sudo pip3 install "conan==1.58.0";
+        conan install .. -pr:h ../conanprofiles/clang-libcpp -pr:b ../conanprofiles/clang-libcpp;
     - name: Configure CMake
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
       # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type

.github/workflows/native-build.yml

@@ -43,7 +43,10 @@ jobs:
         submodules: 'recursive'
 
     - name: Install dependencies
-      run:  sudo apt update && sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
+      run:  |
+        sudo gem install apt-spy2 && sudo apt-spy2 fix --commit --launchpad --country=US
+        sudo apt-get update
+        sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
     - name: Install boost Ubuntu 22.04
       run : sudo apt update && sudo apt install -y libboost-all-dev
     - name: Install gcc 11

.github/workflows/upload-sonarcloud.yml

@@ -109,7 +109,11 @@ jobs:
       - name: Install sonar-scanner and build-wrapper
         uses: SonarSource/sonarcloud-github-c-cpp@v1
       - name: Install dependencies
-        run:  sudo apt update && sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
+        run:  |
+          sudo gem install apt-spy2
+          sudo apt-spy2 fix --commit --launchpad --country=US
+          sudo apt-get update
+          sudo apt-get install -y libicu-dev tzdata gcc-10 libzstd-dev libjemalloc-dev
       - name: Install boost Ubuntu 22.04
         run : sudo apt update && sudo apt install -y libboost-all-dev
       - name: Install clang 16

.gitignore

@@ -43,7 +43,9 @@ e2e_data/*
 # ctags generated tag file
 tags
 src/tags
-/build/
 sourcelist
 .cache/
 .vscode/
+
+/cmake-build*
+/localIndices