bump up container image versions and drop using CPack

We have already provided DEB packages in launchpad PPA and RPM packages
in COPR. Thus, we need no more deb/rpm packages in Github releases. The
single binary build of mscp is an execptio.

Updated container image versions:
- almalinux	8.8  -> 9.3
- rocky		8.8  -> 8.9, and 9.3 is added
- alpine	3.17 -> 3.19

Dockerfile/.gitignore

@@ -0,0 +1,3 @@
+
+# generated by cmake
+rpmbuild.Dockerfile