chore: add gosec nosec directives for controlled environment variables

[jplanckeel]

• Add #nosec G107 directives to http.Get() calls in catalog.go
• Add #nosec G107 directives to http.Get() call in cron.go fetchEvents()
• Add #nosec G107 directives to http.Get() call in cron.go fetchEventsToSync()
• Add #nosec G107 directives to http.NewRequest() calls in slack.go postTrackerChangeLog()
• Add #nosec G107 directives to http.DefaultClient.Do() call in slack.go postTrackerChangeLog()
• Add #nosec G107 directives to http.NewRequest() and header operations in slack.go postTrackerEvent()
• Add #nosec G107 directives to http.NewRequest() call in slack.go editTrackerEvent()
• Add #nosec G107 directives to http.NewRequest() call in slack.go updateTrackerEvent()
• Add #nosec G107 directives to http.DefaultClient.Do() call in slack.go updateTrackerEvent()
• Add #nosec G107 directives to json.Marshal() and http.NewRequest() calls in slack.go updateTrackerEventSlackId()
• Suppress gosec G107 warnings for TRACKER_HOST environment variable usage across all HTTP operations

Description

Please include a summary of the changes and the related issue. Please also include relevant motivation and context. List any dependencies that are required for this change.

Fixes # (issue)

Type of change

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• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Test A
• Test B

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules