Bump http-proxy from 1.17.0 to 1.18.1 in /demo

Bumps [http-proxy](https://github.com/http-party/node-http-proxy) from 1.17.0 to 1.18.1.
- [Release notes](https://github.com/http-party/node-http-proxy/releases)
- [Changelog](https://github.com/http-party/node-http-proxy/blob/master/CHANGELOG.md)
- [Commits](http-party/node-http-proxy@1.17.0...1.18.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

demo/yarn.lock

@@ -2811,13 +2811,6 @@ [email protected], debug@^2.1.2, debug@^2.2.0, debug@^2.3.3, debug@^2.6.0, debug@^2.6.
   dependencies:
     ms "2.0.0"
 
-debug@=3.1.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/debug/-/debug-3.1.0.tgz#5bb5a0672628b64149566ba16819e61518c67261"
-  integrity sha512-OX8XqP7/1a9cqkxYw2yXss15f26NKWBpDXQd0/uK/KPqdQhxbPa994hnzjcE2VqQpDslf55723cKPUOGSmMY3g==
-  dependencies:
-    ms "2.0.0"
-
 debug@^3.1.0:
   version "3.2.6"
   resolved "https://registry.yarnpkg.com/debug/-/debug-3.2.6.tgz#e83d17de16d8a7efb7717edbe5fb10135eee629b"
@@ -3459,10 +3452,10 @@ etag@~1.8.1:
   resolved "https://registry.yarnpkg.com/etag/-/etag-1.8.1.tgz#41ae2eeb65efa62268aebfea83ac7d79299b0887"
   integrity sha1-Qa4u62XvpiJorr/qg6x9eSmbCIc=
 
-eventemitter3@^3.0.0:
-  version "3.1.0"
-  resolved "https://registry.yarnpkg.com/eventemitter3/-/eventemitter3-3.1.0.tgz#090b4d6cdbd645ed10bf750d4b5407942d7ba163"
-  integrity sha512-ivIvhpq/Y0uSjcHDcOIccjmYjGLcP09MFGE7ysAwkAvkXfpZlC985pH2/ui64DKazbTW/4kN3yqozUxlXzI6cA==
+eventemitter3@^4.0.0:
+  version "4.0.7"
+  resolved "https://registry.yarnpkg.com/eventemitter3/-/eventemitter3-4.0.7.tgz#2de9b68f6528d5644ef5c59526a1b4a07306169f"
+  integrity sha512-8guHBZCwKnFhYdHr2ysuRWErTwhoN2X8XELRlrRwpmfeY2jjuUN4taQMsULKUVo1K4DvZl+0pgfyoysHxvmvEw==
 
 events@^1.0.0:
   version "1.1.1"
@@ -3870,11 +3863,9 @@ flush-write-stream@^1.0.0:
     readable-stream "^2.0.4"
 
 follow-redirects@^1.0.0:
-  version "1.5.9"
-  resolved "https://registry.yarnpkg.com/follow-redirects/-/follow-redirects-1.5.9.tgz#c9ed9d748b814a39535716e531b9196a845d89c6"
-  integrity sha512-Bh65EZI/RU8nx0wbYF9shkFZlqLP+6WT/5FnA3cE/djNSuKNHJEinGGZgu/cQEkeeb2GdFOgenAmn8qaqYke2w==
-  dependencies:
-    debug "=3.1.0"
+  version "1.13.0"
+  resolved "https://registry.yarnpkg.com/follow-redirects/-/follow-redirects-1.13.0.tgz#b42e8d93a2a7eea5ed88633676d6597bc8e384db"
+  integrity sha512-aq6gF1BEKje4a9i9+5jimNFIpq4Q1WiwBToeRK5NvZBd/TRsmW8BsJfOEGkr76TbOyPVD3OVDN910EcUNtRYEA==
 
 for-in@^0.1.3:
   version "0.1.8"
@@ -4491,11 +4482,11 @@ http-proxy-middleware@~0.18.0:
     micromatch "^3.1.9"
 
 http-proxy@^1.16.2:
-  version "1.17.0"
-  resolved "https://registry.yarnpkg.com/http-proxy/-/http-proxy-1.17.0.tgz#7ad38494658f84605e2f6db4436df410f4e5be9a"
-  integrity sha512-Taqn+3nNvYRfJ3bGvKfBSRwy1v6eePlm3oc/aWVxZp57DQr5Eq3xhKJi7Z4hZpS8PC3H4qI+Yly5EmFacGuA/g==
+  version "1.18.1"
+  resolved "https://registry.yarnpkg.com/http-proxy/-/http-proxy-1.18.1.tgz#401541f0534884bbf95260334e72f88ee3976549"
+  integrity sha512-7mz/721AbnJwIVbnaSv1Cz3Am0ZLT/UBwkC92VlxhXv/k/BBQfM2fXElQNC27BVGr0uwUpplYPQM9LnaBMR5NQ==
   dependencies:
-    eventemitter3 "^3.0.0"
+    eventemitter3 "^4.0.0"
     follow-redirects "^1.0.0"
     requires-port "^1.0.0"