Update linux.yml

Author: raysan5

.github/workflows/linux.yml

@@ -80,6 +80,9 @@ jobs:
     - name: Generate Artifacts
       run: |
         cp -v ./src/raylib.h ./build/${{ env.RELEASE_NAME }}/include
+        cp -v ./src/raymath.h ./build/${{ env.RELEASE_NAME }}/include
+        cp -v ./src/rlgl.h ./build/${{ env.RELEASE_NAME }}/include
+        cp -v ./src/extras/raygui.h ./build/${{ env.RELEASE_NAME }}/include
         cp -v ./README.md ./build/${{ env.RELEASE_NAME }}/README.md
         cp -v ./LICENSE ./build/${{ env.RELEASE_NAME }}/LICENSE
         cd build