Forcing wget to use IPv4

[jasonjanderson]

Ran into an issue where the wget calls were failing with the following error:

+ '[' -n /github/workspace ']'
+ cd /github/workspace
+ TFSEC_VERSION=latest
+ '[' -n latest
/entrypoint.sh: line [14](https://github.com/jasonjanderson/terraform-test/actions/runs/3323368838/jobs/5493621746#step:5:15): [: missing `]'
++ grep -m 1 -o -E 'https://.+?tfsec-linux-amd64'
++ wget -q https://api.github.com/repos/aquasecurity/tfsec/releases/latest -O -
++ head -n1
wget: bad address 'api.github.com'
+ wget -O - -q ''
wget: bad address ''

Seems like the default busybox version of wget has issues when using a IPv6 network interface: https://stackoverflow.com/questions/66115118/wget-unable-to-resolve-host-address-github-com-inside-alpine-docker-image

Updated image to use the alpine version of wget and forcing IPv4 like what's suggested in the article.

Before change: https://github.com/jasonjanderson/terraform-test/actions/runs/3323368838/jobs/5493621746
After change: https://github.com/jasonjanderson/terraform-test/actions/runs/3324210862/jobs/5495510589

[CLAassistant]

All committers have signed the CLA.

[jasonjanderson]

@owenrumney Tagging you since you have the most recent commit. Thoughts on this change?

[owenrumney]

thanks LGTM

[ilmax]

Hey @jasonjanderson is it me or this PR broke the install of tfsec to the latest version? Now it's hardcoded to v1.28.1