Update build.yml

With libmsgpackc2

Author: sbernhard

.github/workflows/build.yml

@@ -44,7 +44,7 @@ jobs:
     - name: Test to create neoVim AppImage
       run: |
         apt-get update
-        apt-get install -y lua-luv
+        apt-get install -y lua-luv libmsgpackc2
         chmod +x ./out/pkg2appimage*.AppImage*
         ./out/pkg2appimage*.AppImage* recipes/neovim.yml