fix(docs): remove duplicate link in changelog file (TooTallNate#211)

Author: guoard

CHANGELOG.md

@@ -8,7 +8,6 @@ Each package in this monorepo has an individual changelog:
 * [`get-uri`](packages/get-uri/CHANGELOG.md)
 * [`http-proxy-agent`](packages/http-proxy-agent/CHANGELOG.md)
 * [`https-proxy-agent`](packages/https-proxy-agent/CHANGELOG.md)
-* [`https-proxy-agent`](packages/https-proxy-agent/CHANGELOG.md)
 * [`pac-proxy-agent`](packages/pac-proxy-agent/CHANGELOG.md)
 * [`pac-resolver`](packages/pac-resolver/CHANGELOG.md)
 * [`proxy`](packages/proxy/CHANGELOG.md)