Bump koa from 2.13.4 to 2.15.4

Bumps [koa](https://github.com/koajs/koa) from 2.13.4 to 2.15.4.
- [Release notes](https://github.com/koajs/koa/releases)
- [Changelog](https://github.com/koajs/koa/blob/2.15.4/History.md)
- [Commits](https://github.com/koajs/koa/compare/2.13.4...2.15.4)

---
updated-dependencies:
- dependency-name: koa
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>

yarn.lock

@@ -8721,10 +8721,10 @@ cookie@0.5.0:
   resolved "https://registry.npmjs.org/cookie/-/cookie-0.5.0.tgz"
   integrity sha512-YZ3GUyn/o8gfKJlnlX7g7xq4gyO6OSuhGPKaaGssGB2qgDUS0gPgtTvoyZLTt9Ab6dC4hfc9dV5arkvc/OCmrw==
 
-cookies@~0.8.0:
-  version "0.8.0"
-  resolved "https://registry.npmjs.org/cookies/-/cookies-0.8.0.tgz"
-  integrity sha512-8aPsApQfebXnuI+537McwYsDtjVxGm8gTIzQI3FDW6t5t/DAhERxtnbEPN/8RX+uZthoz4eCOgloXaE5cYyNow==
+cookies@~0.9.0:
+  version "0.9.1"
+  resolved "https://registry.yarnpkg.com/cookies/-/cookies-0.9.1.tgz#3ffed6f60bb4fb5f146feeedba50acc418af67e3"
+  integrity sha512-TG2hpqe4ELx54QER/S3HQ9SRVnQnGBtKUz5bLQWtYAQ+o6GpgMs6sYUvaiJjVxb+UXwhRhAEP3m7LbsIZ77Hmw==
   dependencies:
     depd "~2.0.0"
     keygrip "~1.1.0"
@@ -13521,15 +13521,15 @@ koa-static@^5.0.0:
     koa-send "^5.0.0"
 
 koa@^2.5.3:
-  version "2.13.4"
-  resolved "https://registry.npmjs.org/koa/-/koa-2.13.4.tgz"
-  integrity sha512-43zkIKubNbnrULWlHdN5h1g3SEKXOEzoAlRsHOTFpnlDu8JlAOZSMJBLULusuXRequboiwJcj5vtYXKB3k7+2g==
+  version "2.15.4"
+  resolved "https://registry.yarnpkg.com/koa/-/koa-2.15.4.tgz#7000b3d8354558671adb1ba1b1c09bedb5f8da75"
+  integrity sha512-7fNBIdrU2PEgLljXoPWoyY4r1e+ToWCmzS/wwMPbUNs7X+5MMET1ObhJBlUkF5uZG9B6QhM2zS1TsH6adegkiQ==
   dependencies:
     accepts "^1.3.5"
     cache-content-type "^1.0.0"
     content-disposition "~0.5.2"
     content-type "^1.0.4"
-    cookies "~0.8.0"
+    cookies "~0.9.0"
     debug "^4.3.2"
     delegates "^1.0.0"
     depd "^2.0.0"