Modify the regex for name on import public key form

This patch fix does not match the regex in horizon and nova [1].

The service supports underscores, but the restriction imposed in horizon
is different, so the regex is updated.

[1] 6ebb2c4cae/nova/compute/api.py (L5674-L5690)

Change-Id: Icc5e9c6447253d6087c578ab931b52a923128e38

openstack_dashboard/static/app/core/keypairs/actions/import.service.js

@@ -49,7 +49,7 @@
         "name": {
           title: gettext("Key Pair Name"),
           type: "string",
-          pattern: "^[A-Za-z0-9 -]+$"
+          pattern: "^[A-Za-z0-9 _-]+$"
         },
         "key_type": {
           title: gettext("Key Type"),