Tentatively fix the version of tfsec at v1.28.1

[yu-iskw]

The GitHub Actions doesn't work with the latest version tfsec v1.28.2. So, it would be good to tentatively fix the tfsec version with v1.28.1 right now, as it may take a bit time to identify the root cause of breaking changes on the tfsec side.

[thaim]

This is because tfsec v1.28.2 adds a transition message. tfsec print a message even if the json format is specified.
It seems that there is no option to suppress this message.

$ tfsec1282 . --format json 

======================================================
tfsec is joining the Trivy family

tfsec will continue to remain available 
for the time being, although our engineering 
attention will be directed at Trivy going forward.

You can read more here: 
https://github.com/aquasecurity/tfsec/discussions/1994
======================================================
{
	"results": []
}

aquasecurity/tfsec#2067

[yu-iskw]

@thaim Nice catch. I have sent a pull request to tfsec so that tfsec print out the transition message as standard error. By doing so, we are able to parse the result of JSON format of tfsec with JSON parsers like jq.

aquasecurity/tfsec#2099

[shogo82148]

closed by #98