Update dependency koa to ^2.13.0

package.json

@@ -18,7 +18,7 @@
   "dependencies": {
     "@ianwalter/print": "^5.0.0",
     "@ianwalter/router": "^1.3.0",
-    "koa": "^2.8.1",
+    "koa": "^2.13.0",
     "koa-json": "^2.0.2"
   },
   "eslintConfig": {

yarn.lock

@@ -1348,11 +1348,6 @@ error-ex@^1.2.0, error-ex@^1.3.1:
   dependencies:
     is-arrayish "^0.2.1"
 
-error-inject@^1.0.0:
-  version "1.0.0"
-  resolved "https://registry.yarnpkg.com/error-inject/-/error-inject-1.0.0.tgz#e2b3d91b54aed672f309d950d154850fa11d4f37"
-  integrity sha1-4rPZG1Su1nLzCdlQ0VSFD6EdTzc=
-
 es-abstract@^1.17.0, es-abstract@^1.17.0-next.1, es-abstract@^1.17.2:
   version "1.17.4"
   resolved "https://registry.yarnpkg.com/es-abstract/-/es-abstract-1.17.4.tgz#e3aedf19706b20e7c2594c35fc0d57605a79e184"
@@ -2618,10 +2613,10 @@ koa-json@^2.0.2:
     koa-is-json "1"
     streaming-json-stringify "3"
 
-koa@^2.8.1:
-  version "2.11.0"
-  resolved "https://registry.yarnpkg.com/koa/-/koa-2.11.0.tgz#fe5a51c46f566d27632dd5dc8fd5d7dd44f935a4"
-  integrity sha512-EpR9dElBTDlaDgyhDMiLkXrPwp6ZqgAIBvhhmxQ9XN4TFgW+gEz6tkcsNI6BnUbUftrKDjVFj4lW2/J2aNBMMA==
+koa@^2.13.0:
+  version "2.13.0"
+  resolved "https://registry.yarnpkg.com/koa/-/koa-2.13.0.tgz#25217e05efd3358a7e5ddec00f0a380c9b71b501"
+  integrity sha512-i/XJVOfPw7npbMv67+bOeXr3gPqOAw6uh5wFyNs3QvJ47tUx3M3V9rIE0//WytY42MKz4l/MXKyGkQ2LQTfLUQ==
   dependencies:
     accepts "^1.3.5"
     cache-content-type "^1.0.0"
@@ -2633,7 +2628,6 @@ koa@^2.8.1:
     depd "^1.1.2"
     destroy "^1.0.4"
     encodeurl "^1.0.2"
-    error-inject "^1.0.0"
     escape-html "^1.0.3"
     fresh "~0.5.2"
     http-assert "^1.3.0"