deps: Bump serve-static to latest, 1.16.2

Taking this upgrade because we learned from dependabot that it fixes
a security issue:
  #5887

The issue is in a dev-only indirect dependency, and even our
development tools *probably* don't trigger it.  But I can't
rule out that they might.

The yarn.lock diff from dependabot is a bit messy, though,
so here's me doing the same upgrade directly.

---

Because this is an indirect dependency, `yarn upgrade serve-static`
just does nothing.  (Seems like a bug / misfeature in Yarn.)

And I don't want to do a general `yarn upgrade` in this legacy
codebase right now -- that would balloon into a larger task.

So, here's a fun technique to make the upgrade in a surgical way:

  $ perl -i -0pe 's{^serve-static@.*?\n\K.*?^$}
                   {  version "1.16.2"\n}sm
                 ' yarn.lock
  $ yarn

That deletes the "version", "resolved", and other fields in the
lockfile's resolution of the `serve-static` package, replacing them
with just a "version" line pointing at the desired version.

Then rerunning `yarn` (aka `yarn install`) starts from that version
when filling back in the rest of the details.

yarn.lock

@@ -5121,6 +5121,11 @@ encodeurl@~1.0.2:
   resolved "https://registry.yarnpkg.com/encodeurl/-/encodeurl-1.0.2.tgz#ad3ff4c86ec2d029322f5a02c3a9a606c95b3f59"
   integrity sha512-TPJXq8JqFaVYm2CWmPvnP2Iyo4ZSM7/QKcSmuMLDObfpH5fi7RUGmd/rTDf+rut/saiDiQEeVTNgAmJEdAOx0w==
 
+encodeurl@~2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/encodeurl/-/encodeurl-2.0.0.tgz#7b8ea898077d7e409d3ac45474ea38eaf0857a58"
+  integrity sha512-Q0n9HRi4m6JuGIV1eFlmvJB7ZEVxu93IrMyiMsGC0lrMJMWzRgx6WGquyfQgZVb31vhGgXnfmPNNXmxnOkRBrg==
+
 encoding@^0.1.12, encoding@^0.1.13:
   version "0.1.13"
   resolved "https://registry.yarnpkg.com/encoding/-/encoding-0.1.13.tgz#56574afdd791f54a8e9b2785c0582a2d26210fa9"
@@ -11500,10 +11505,10 @@ semver@^7.3.2, semver@^7.3.5, semver@^7.3.7, semver@^7.5.3, semver@^7.5.4:
   dependencies:
     lru-cache "^6.0.0"
 
-send@0.18.0:
-  version "0.18.0"
-  resolved "https://registry.yarnpkg.com/send/-/send-0.18.0.tgz#670167cc654b05f5aa4a767f9113bb371bc706be"
-  integrity sha512-qqWzuOjSFOuqPjFe4NOsMLafToQQwBSOEpS+FwEt3A2V3vKubTquT3vmLTQpFgMXp8AlFWFuP1qKaJZOtPpVXg==
+send@0.19.0:
+  version "0.19.0"
+  resolved "https://registry.yarnpkg.com/send/-/send-0.19.0.tgz#bbc5a388c8ea6c048967049dbeac0e4a3f09d7f8"
+  integrity sha512-dW41u5VfLXu8SJh5bwRmyYUbAoSB3c9uQh6L8h/KtsFREPWpbX1lrljJo186Jc4nmci/sGUZ9a0a0J2zgfq2hw==
   dependencies:
     debug "2.6.9"
     depd "2.0.0"
@@ -11532,14 +11537,14 @@ serialize-error@^2.1.0:
   integrity sha512-ghgmKt5o4Tly5yEG/UJp8qTd0AN7Xalw4XBtDEKP655B699qMEtra1WlXeE6WIvdEG481JvRxULKsInq/iNysw==
 
 serve-static@^1.13.1:
-  version "1.15.0"
-  resolved "https://registry.yarnpkg.com/serve-static/-/serve-static-1.15.0.tgz#faaef08cffe0a1a62f60cad0c4e513cff0ac9540"
-  integrity sha512-XGuRDNjXUijsUL0vl6nSD7cwURuzEgglbOaFuZM9g3kwDXOWVTck0jLzjPzGD+TazWbboZYu52/9/XPdUgne9g==
+  version "1.16.2"
+  resolved "https://registry.yarnpkg.com/serve-static/-/serve-static-1.16.2.tgz#b6a5343da47f6bdd2673848bf45754941e803296"
+  integrity sha512-VqpjJZKadQB/PEbEwvFdO43Ax5dFBZ2UECszz8bQ7pi7wt//PWe1P6MN7eCnjsatYtBT6EuiClbjSWP2WrIoTw==
   dependencies:
-    encodeurl "~1.0.2"
+    encodeurl "~2.0.0"
     escape-html "~1.0.3"
     parseurl "~1.3.3"
-    send "0.18.0"
+    send "0.19.0"
 
 set-blocking@^2.0.0:
   version "2.0.0"