Upgrade gitiles-servlet to 0.2-7.1

Version 0.2-7 is quite old and does not include fixes that have
since been included in versions up to the latest 0.2-11 and on the
stable-0.2 branch.

In particular, [1] which was causing Gerrit JVM GC to start a series
of 'stop-the-world' when rendering large files, has been fixed in the
latest stable-0.2.

We cannot upgrade directly to 0.2-11 because that also includes updates
to JGit and soy which are not compatible with core Gerrit's 2.16 series.
Hence, 0.2-7.1 has been released which includes all of the bug fixes
and improvements, but not the library upgrades

[1] https://github.com/google/gitiles/issues/192

Change-Id: Iaad970f0400d14bd6c51fc1720aa12cc1b56c82a

external_plugin_deps.bzl

diff --git a/external_plugin_deps.bzl b/external_plugin_deps.bzl
index 5f4313d..3efba09 100644
--- a/external_plugin_deps.bzl
+++ b/external_plugin_deps.bzl
@@ -5,8 +5,8 @@
 def external_plugin_deps():
     maven_jar(
         name = "gitiles-servlet",
-        artifact = "com.google.gitiles:gitiles-servlet:0.2-7",
-        sha1 = "f23b22cb27fe5c4a78f761492082159d17873f57",
+        artifact = "com.google.gitiles:gitiles-servlet:0.2-7.1",
+        sha1 = "669579c0921c8a258bb6808cad7d597e06eb0f57",
         repository = GERRIT,
     )