[bug] sarif format doesn't support "tf-var" arg

[antigenius0910]

Hi team, thanks for the awesome project. we follow you from tf-sec to here and would love to contribute and make this codebase as awesome as possible.

We really want to use the sarif and codeql function so we can integrate all the GitHub code scan result to JIRA.

when we use below setting, everything works as expected.

      - name: Run Trivy vulnerability scanner in IaC mode
        uses: aquasecurity/trivy-action@master
        with:
          scan-type: config
          hide-progress: false
          tf-vars: ${{ inputs.working-directory }}/terraform.tfvars.json
          format: table
          exit-code: 1
          ignore-unfixed: false
          severity: CRITICAL,HIGH,MEDIUM

result looks great vun misconfig has been found!

Running trivy with options: trivy config  --format table --exit-code  1 --severity  CRITICAL,HIGH,MEDIUM --tf-vars  ./terraform/terraform.tfvars.json .
Global options:  
2024-02-16T15:42:06.213Z	INFO	Misconfiguration scanning is enabled
2024-02-16T15:42:06.213Z	INFO	Need to update the built-in policies
2024-02-16T15:42:06.213Z	INFO	Downloading the built-in policies...
45.79 KiB / 45.79 KiB [-----------------------------------------------------------] 100.00% ? p/s 0s2024-02-16T15:42:07.417Z	INFO	Detected config files: 2

Then we switch to the format you suggested on README here https://github.com/aquasecurity/trivy-action/blob/master/README.md?plain=1#L286-L300

      - name: Run Trivy vulnerability scanner in IaC mode
        uses: aquasecurity/trivy-action@master
        with:
          scan-type: 'config'
          hide-progress: false
          tf-vars: ${{ inputs.working-directory }}/terraform.tfvars.json
          format: 'sarif'
          output: 'trivy-results.sarif'
          exit-code: '1'
          ignore-unfixed: false
          severity: CRITICAL,HIGH,MEDIUM

seems like nothing has been scanned

Building SARIF report with options:  --exit-code  1 .

can you take a look on this discrepancy and point out what we might config wrongly? thanks.

[antigenius0910]

PR here #311 for fixing the bug. thanks