install properly?

.github/workflows/ci.yml

@@ -154,7 +154,7 @@ jobs:
           ~/extern/lib
           ~/extern/include
         # Change this key if we start caching more things
-        key: extern-${{ github.job }}-${{ matrix.name }}-v1
+        key: extern-${{ github.job }}-${{ matrix.name }}-v2
 
     - name: Setup environment
       # These add to PATH-like variables, so they can always be set
@@ -174,9 +174,6 @@ jobs:
         sudo apt-get update
         sudo apt-get -y install clang valgrind
 
-    - name: Install libdispatch
-      run: sudo apt-get -y install libdispatch-dev
-
     - name: Install cross compilation tools
       if: matrix.target == 'i686-unknown-linux-gnu'
       run: |
@@ -190,6 +187,20 @@ jobs:
       if: steps.extern-cache.outputs.cache-hit != 'true'
       run: sudo apt-get -y install make cmake
 
+    - name: Install libdispatch
+      if: steps.extern-cache.outputs.cache-hit != 'true'
+      run: |
+        wget https://github.com/swiftlang/swift-corelibs-libdispatch/archive/refs/tags/swift-6.0.3-RELEASE.tar.gz
+        tar -xzf swift-corelibs-libdispatch-swift-6.0.3-RELEASE.tar.gz
+        cd swift-corelibs-libdispatch-swift-6.0.3-RELEASE
+
+        mkdir build
+        cd build
+        cmake -Wno-dev -DCMAKE_INSTALL_PREFIX=$HOME/extern ..
+        make install
+        ldconfig
+        ls -al $HOME/extern/*
+
     - name: Install GNUStep libobjc2
       if: steps.extern-cache.outputs.cache-hit != 'true'
       run: |