feat: avoid setting privileged flag if seLinuxOptions is not null (#599)

Sets the privileged flag to false if SELinuxOptions are present/defined. This is needed because containerd treats SELinux and Privileged controls as mutually exclusive. Also see https://github.com/containerd/cri/blob/aa2d5a97c/pkg/server/container_create.go#L164.

This allows users who use SELinux for managing privileged processes to use GH Actions - otherwise, based on the SELinux policy, the Docker in Docker container might not be privileged enough. 

Signed-off-by: Jonah Back <jonah@jonahback.com>
Co-authored-by: Yusuke Kuoka <ykuoka@gmail.com>

README.md

@@ -728,6 +728,16 @@ spec:
     spec:
       nodeSelector:
         node-role.kubernetes.io/test: ""
+      
+      securityContext:
+        #All level/role/type/user values will vary based on your SELinux policies.
+        #See https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux_atomic_host/7/html/container_security_guide/docker_selinux_security_policy for information about SELinux with containers
+        seLinuxOptions: 
+          level: "s0"
+          role: "system_r"
+          type: "super_t"
+          user: "system_u"
+          
       tolerations:
       - effect: NoSchedule
         key: node-role.kubernetes.io/test