Update lodash (#4317)

Updating lodash from 4.17.19 to 4.17.21.  This was triggered by a bot
that cannot sign the CLA (#4276).
diff --git a/tools/sva/yarn.lock b/tools/sva/yarn.lock
index c46b901..4924690 100644
--- a/tools/sva/yarn.lock
+++ b/tools/sva/yarn.lock
@@ -938,9 +938,9 @@
     path-exists "^3.0.0"
 
 lodash@^4.17.11, lodash@^4.17.12, lodash@^4.17.14:
-  version "4.17.19"
-  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.19.tgz#e48ddedbe30b3321783c5b4301fbd353bc1e4a4b"
-  integrity sha512-JNvd8XER9GQX0v2qJgsaN/mzFCNA5BRe/j8JN9d+tWyGLSodKQHKFicdwNYzWwI3wjRnaKPsGj1XkBjx/F96DQ==
+  version "4.17.21"
+  resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.21.tgz#679591c564c3bffaae8454cf0b3df370c3d6911c"
+  integrity sha512-v2kDEe57lecTulaDIuNTPy3Ry4gLGJ6Z1O3vE1krgXZNrsQ+LFTGHVxVjcXPs17LhbZVGedAJv8XZ1tvj5FvSg==
 
 log-symbols@2.2.0:
   version "2.2.0"