Put vcpkg command in correct stage

.gitlab-ci.yml

@@ -12,6 +12,7 @@ build:
   stage: build
   script:
     # Set the VCPKG_TOOLCHAIN environment variable
+    - vcpkg install freeimage
     - export VCPKG_TOOLCHAIN=$VCPKG_ROOT/scripts/buildsystems/vcpkg.cmake
     - mkdir -p build
     - cmake -B build -S . -G Ninja -DCMAKE_TOOLCHAIN_FILE=$VCPKG_TOOLCHAIN