Updated python packages to address docker container failing to build

[ericmartin]

Added: py3-pip

Changed: py-lxml -> py3-lxml

When you attempt to build Dockerfile, you get an error due to package name changes in alpine:

docker build .
[+] Building 1.2s (6/8)                                                                                                                   
 => [internal] load build definition from Dockerfile                                                                                 0.0s
 => => transferring dockerfile: 1.74kB                                                                                               0.0s
 => [internal] load .dockerignore                                                                                                    0.0s
 => => transferring context: 2B                                                                                                      0.0s
 => [internal] load metadata for docker.io/library/alpine:latest                                                                     0.0s
 => CACHED [1/4] FROM docker.io/library/alpine:latest                                                                                0.0s
 => CACHED https://raw.githubusercontent.com/salesforce/hassh/master/python/hassh.py                                                 0.0s
 => ERROR [2/4] RUN apk --no-cache add python3 gcc     py-lxml tshark     && pip3 install pyshark                                    1.1s
------                                                                                                                                    
 > [2/4] RUN apk --no-cache add python3 gcc     py-lxml tshark     && pip3 install pyshark:                                               
#5 0.259 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz                                                    
#5 0.758 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
#5 1.012 ERROR: unable to select packages:
#5 1.064   py-lxml (no such package):
#5 1.064     required by: world[py-lxml]
------
executor failed running [/bin/sh -c apk --no-cache add python3 gcc     py-lxml tshark     && pip3 install pyshark]: exit code: 1

This updates the packages and allows the Dockerfile to build and run properly

[salesforce-cla[bot]]

Thanks for the contribution! Unfortunately we can't verify the commit author(s): Eric Martin e***@e***.com. One possible solution is to add that email to your GitHub account. Alternatively you can change your commits to another email and force push the change. After getting your commits associated with your GitHub account, sign the Salesforce.com Contributor License Agreement and this Pull Request will be revalidated.

[ericmartin]

I signed the CLA, no idea why this is still marked as unhandled.