bump rustfmt to include fix for failing tests

pietroalbini · pietroalbini · commit 59a6d31a2869 · 2020-03-11T23:05:55.000+01:00
diff --git a/src/tools/rustfmt b/src/tools/rustfmt
@@ -1 +1 @@
-Subproject commit 9f53665f91be16c9aa7afd83f7c79357fec9152b
+Subproject commit a828ffea992db2085aa13822a69acb74fa1bde31
