app/matrix: appservice-irc: use secret in bootstrap job

Previously: 856b2164591512d025fae9c1ba27fbc12a876cf6 switched to using a
Secret instead of a ConfigMap for appservice-irc. That however didn't
update the bootstrap job which still used the ConfigMap. This fixes
that.

Change-Id: I50f33935691678ce24ecf4e04d7ce1b13c184929
diff --git a/app/matrix/lib/appservice-irc.libsonnet b/app/matrix/lib/appservice-irc.libsonnet
index fd51e4e..7906463 100644
--- a/app/matrix/lib/appservice-irc.libsonnet
+++ b/app/matrix/lib/appservice-irc.libsonnet
@@ -70,7 +70,7 @@
                 template+: {
                     spec+: {
                         volumes_: {
-                            config: kube.ConfigMapVolume(bridge.config),
+                            config: kube.SecretVolume(bridge.config),
                         },
                         containers_: {
                             bootstrap: kube.Container("appservice-irc-%s-bootstrap" % [name]) {