Feature: Add support for --ignore-unfixed

[zoispag]

Closes #9

This PR adds support for --ignore-unfixed run argument.

I took the liberty and updated the README.me to point to tag 0.0.7.

Test

- name: Run scanner with --ignore-fixed=false
  uses: zoispag/trivy-action@master
  if: always()
  with:
    image-ref: 'image'
    exit-code: '1'
    severity: 'MEDIUM'
    ignore-unfixed: false

- name: Run scanner with --ignore-fixed not set
  uses: zoispag/trivy-action@master
  if: always()
  with:
    image-ref: 'image'
    exit-code: '1'
    severity: 'MEDIUM'

- name: Run scanner with --ignore-fixed=true
  uses: zoispag/trivy-action@master
  if: always()
  with:
    image-ref: 'image'
    exit-code: '1'
    severity: 'MEDIUM'
    ignore-unfixed: true

• Run scanner with --ignore-fixed=false executes: docker.io/aquasec/trivy:latest "image" "--format=table" "--ignore-unfixed=false" "--exit-code=1" "--severity=MEDIUM" "image"
• Run scanner with --ignore-fixed not set executes: docker.io/aquasec/trivy:latest "image" "--format=table" "--ignore-unfixed=false" "--exit-code=1" "--severity=MEDIUM" "image"
• Run scanner with --ignore-fixed=true executes: docker.io/aquasec/trivy:latest "image" "--format=table" "--ignore-unfixed=true" "--exit-code=1" "--severity=MEDIUM" "image"

[danielpacak]

LGTM @zoispag ! Thank you for contributing and testing the action with different settings 💯