ci/main: remove redundant default shell
ci/main: remove redundant default shell

Signed-off-by: Unai Martinez-Corral <077fe90a36ffc14124d0102ab2e6dffd2176da93@antmicro.com>

chipsalliance/Surelog,alainmarcel/Surelog,alainmarcel/Surelog,chipsalliance/Surelog,chipsalliance/Surelog,alainmarcel/Surelog,alainmarcel/Surelog,chipsalliance/Surelog