this test has failed on drone :/

Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au>

tests/kernel_headers_test.go

@@ -6,6 +6,6 @@ func (s *QemuSuite) TestKernelHeaders(c *C) {
 	s.RunQemu(c, "--cloud-config", "./tests/assets/test_22/cloud-config.yml")
 
 	s.CheckCall(c, `
-sleep 15
+sleep 30
 docker inspect kernel-headers`)
 }