perfdata: update to Go 1.13 and larger instance

The default F1 instance was running out of memory.
Give it more memory.
Also update to Go 1.13 because Go 1.11 instances get less memory for some reason.

Change-Id: I4c7b790f2281449a3e0a8e8de17f24d5af22ed9a
Reviewed-on: https://go-review.googlesource.com/c/perf/+/220658
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

storage/appengine/app.yaml

diff --git a/storage/appengine/app.yaml b/storage/appengine/app.yaml
index ddab39d..ebea554 100644
--- a/storage/appengine/app.yaml
+++ b/storage/appengine/app.yaml
@@ -1,5 +1,6 @@
-runtime: go111
+runtime: go113
 service: perfdata
+instance_class: F4_HIGHMEM
 
 handlers:
   - url: /_ah/remote_api