Add vcpkg cache, hopefully works.

.github/workflows/build.yaml

@@ -25,6 +25,20 @@ jobs:
           sudo apt-get update
           sudo apt-get install -y build-essential ninja-build ccache uuid-dev
 
+      - name: Restore vcpkg Cache
+        uses: actions/cache@v5
+        with:
+          path: |
+            submodules/vcpkg/buildtrees
+            submodules/vcpkg/downloads
+            submodules/vcpkg/installed
+            submodules/vcpkg/packages
+            submodules/vcpkg/vcpkg.exe
+            submodules/vcpkg/vcpkg
+          key: ${{ runner.os }}-vcpkg-${{ hashFiles('vcpkg.json', 'submodules/vcpkg/.git/HEAD') }}
+          restore-keys: |
+            ${{ runner.os }}-vcpkg-
+
       - name: Configure
         run: |
           cmake -S . -B build -G Ninja \
@@ -61,6 +75,20 @@ jobs:
         with:
           arch: x64
 
+      - name: Restore vcpkg Cache
+        uses: actions/cache@v5
+        with:
+          path: |
+            submodules/vcpkg/buildtrees
+            submodules/vcpkg/downloads
+            submodules/vcpkg/installed
+            submodules/vcpkg/packages
+            submodules/vcpkg/vcpkg.exe
+            submodules/vcpkg/vcpkg
+          key: ${{ runner.os }}-vcpkg-${{ hashFiles('vcpkg.json', 'submodules/vcpkg/.git/HEAD') }}
+          restore-keys: |
+            ${{ runner.os }}-vcpkg-
+
       - name: Configure
         shell: pwsh
         run: |