Don't try to reinstall KSC after it's been installed from GH Releases

See kaitai-io/kaitai_compress#7 (comment)

Although it doesn't do anything wrong, it's unnecessary.

.github/workflows/main.yml

@@ -27,7 +27,7 @@ jobs:
           sudo apt-get install --no-install-recommends -y \
             git ssh \
             locales \
-            kaitai-struct-compiler default-jre-headless \
+            default-jre-headless \
             make gcc libc6-dev \
             graphviz \
             rsync