fix(RootCertificateOpenSsl): migrate NcButton type to variant prop

The 'type' prop for color variants was removed in @nextcloud/vue
v9.0.0 in favour of the 'variant' prop.

Signed-off-by: Vitor Mattos <1079143+vitormattos@users.noreply.github.com>

Author: vitormattos

src/views/Settings/RootCertificateOpenSsl.vue

@@ -97,7 +97,7 @@
 					:disabled="formDisabled" />
 			</div>
 			<NcButton :disabled="!canSave"
-				type="primary"
+				variant="primary"
 				@click="generateCertificate">
 				{{ submitLabel }}
 			</NcButton>