Mount host /etc/ca-certificates (#131)

OSes like Arch Linux put certificate files in /etc/ca-certificates, and symlink to those files from /etc/ssl and /etc/pki.

manifests/system-upgrade-controller.yaml

@@ -95,6 +95,8 @@ spec:
               mountPath: /etc/ssl
             - name: etc-pki
               mountPath: /etc/pki
+            - name: etc-ca-certificates
+              mountPath: /etc/ca-certificates
             - name: tmp
               mountPath: /tmp
       volumes:
@@ -106,5 +108,9 @@ spec:
           hostPath:
             path: /etc/pki
             type: DirectoryOrCreate
+        - name: etc-ca-certificates
+          hostPath:
+            path: /etc/ca-certificates
+            type: DirectoryOrCreate
         - name: tmp
           emptyDir: {}