Bump Jetty to 9.4.31.v20200723 to get rid of Tomcat CVE warnings

Jetty jar has some fixes for transitive CVEs (apache-jsp see details below).

When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50, and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users.

So we need to upgrade jetty 9.4.30+ to get rid of Tomcat CVE warnings

• https://github.com/eclipse/jetty.project/commit/fedc7c65997d433bbdfc26fb3d861f8488f9c804
• https://github.com/eclipse/jetty.project/commit/74a2ce7a4299014d0b8e4549961e7034ae24c3d1

There are also a bunch of other misc fixes:

https://github.com/eclipse/jetty.project/releases