Introduce make targets for sast and address security issues.

[thiyyakat]

What this PR does / why we need it:
This PR introduces two make targets: sast and sast-report to run gosec for Static Application Security Testing. It also addresses the security issues in the repository. The .ci/check script now calls make sast-report to install and run gosec.

Which issue(s) this PR fixes:
Fixes #129

Special notes for your reviewer:
No changes made to the implementation. Only comments added to suppress gosec warnings wherever appropriate.

Release note:

Adding `gosec` for Static Application Security Testing (SAST).

[gardener-robot-ci-1]

This PR proposes changes that would break the pipeline definition:

dependency-watchdog-enh_add-gosec: Traceback (most recent call last):
  File "/usr/lib/python3.12/site-packages/concourse/replicator.py", line 141, in render
    definition_descriptor = self._render(definition_descriptor)
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/concourse/replicator.py", line 185, in _render
    'definition': factory.create_pipeline_definition(),
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib/python3.12/site-packages/concourse/factory.py", line 88, in create_pipeline_definition
    self._apply_traits(variant)
  File "/usr/lib/python3.12/site-packages/concourse/factory.py", line 153, in _apply_traits
    raise ModelValidationError(
model.base.ModelValidationError: JobVariant: head-update: trait requires missing traits: version

[rishabh-11]

/retest-required

[shreyas-s-rao]

@thiyyakat thanks for the PR! I have a few minor comments. PTAL, thanks.

[gardener-robot-ci-2]

The pipeline-definition has been fixed.

[shreyas-s-rao]

/lgtm

[gardener-prow]

LGTM label has been added.

Git tree hash: 1904a5bda09c3616f1a6398973a802ed18e5cb91

[rishabh-11]

/lgtm

[gardener-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: rishabh-11, shreyas-s-rao

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