ci: add explicit workflow permissions

[reubenmiller]

Add explicit workflow permissions to align with security best practices

[github-actions]

Robot Results

✅ Passed	❌ Failed	⏭️ Skipped	Total	Pass %	⏱️ Duration
21	0	1	21	100	8m38.037381999s

Passed Tests

Name	⏱️ Duration	Suite
Supports Cumulocity Basic Auth Credentials	19.565 s	C8Y-Basic-Auth
Ignore Containers Marked With A Specific Label	26.707 s	Container
Grace period to allow container to startup	5.026 s	Operations
Service is up	0.157 s	Operations
Get Logfile Request	2.443 s	Operations
Get Configuration File	4.854 s	Operations
Set Configuration File	2.588 s	Operations
Execute Shell Command	2.447 s	Operations
Install application using docker compose	22.042 s	Operations
Get Container Logs	4.577 s	Operations
Get Container Logs without explicit container name	2.443 s	Operations
Get Container Logs For Non-existent container	2.448 s	Operations
Update From Legacy Versions	137.321 s	Self-Update-Compat
Trigger self update via local command	24.296 s	Self-Update
Self update should only update if there is a new image	19.598 s	Self-Update
Self update using software update operation	104.159 s	Self-Update
Rollback when trying to install a non-tedge based image	19.710 s	Self-Update
Self update using software update operation using Container type	114.541 s	Self-Update
Cloud Connection is Online	0.183 s	Telemetry
Service status	0.305 s	Telemetry
Sends measurements	2.603 s	Telemetry