build: bump megalinter version to v6

[SamPriyadarshi]

What's changed, or what was fixed?

• Bumped megalinter version for Github Actions from v4 to v6 in order to support linting of optional type arguments for Terraform.
• Environment Variables for Mega Linter GitHub Actions workflow were adjusted. Some linters that are currently not being used were disabled to improve the execution time for the Linter phase/
• .hadolint.yaml was added to ignore version pinning errors in Dockerfile (version pinning is not required currently).

Fixes:

• I have run all the tests locally and they all pass.
• I have followed the relevant style guide for my changes.

[g-greatdevaks]

@SamPriyadarshi This new version of Mega Linter seems to be having additional linters.

Please include the following environment variables for the Mega Linter configuration in order to have the linter checks appear similar to v4. Some linters, if disabled, will even have some positive impact on the execution time. For example, TERRAFORM_KICS takes a lot of time and we are having tflint and formatting currently being used.

env:
  ...
  DISABLE_LINTERS: TERRAFORM_KICS,TERRAFORM_CHECKOV,TERRAFORM_TERRASCAN,YAML_YAMLLINT,SPELL_CSPELL,SPELL_PROSELINT,PYTHON_BANDIT,PYTHON_FLAKE8,PYTHON_PYRIGHT,JSON_NPM_PACKAGE_JSON_LINT,REPOSITORY_CHECKOV,REPOSITORY_DEVSKIM,REPOSITORY_DUSTILOCK,REPOSITORY_GITLEAKS,REPOSITORY_GOODCHECK,REPOSITORY_SEMGREP,REPOSITORY_SYFT,REPOSITORY_TRIVY,COPYPASTE_JSCPD
  MARKDOWN_MARKDOWN_LINK_CHECK_DISABLE_ERRORS: true
  ...

[g-greatdevaks]

@SamPriyadarshi Since Hadolint is erroring out because of the version pinning requirement and we don't want to pin to a specific version as of now, we can have the Hadolint check for version pinning ignored.
More information: https://github.com/hadolint/hadolint/wiki/DL3018

.hadolint.yaml => new file created in the root directory

ignored:
  - DL3018

[g-greatdevaks]

LGTM.
Opening an issue (#94) to address the snoozed linters and the ones for which errors have been disabled.

[g-greatdevaks]

LGTM.