Update prom/prometheus Docker tag to v3.12.0

[renovate]

This PR contains the following updates:

Package	Update	Change
prom/prometheus	minor	v3.11.3 → v3.12.0

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Release Notes

prometheus/prometheus (prom/prometheus)

v3.12.0

Compare Source

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[github-actions]

Sonar insights (advisory, no merge-block)

Snapshot of bernstein on the configured Sonar instance:

Metric	Value
Coverage	80.1
Code smells	0
Bugs	0
Vulnerabilities	0
Security hotspots	0

Run bernstein doctor sonar locally for the full surface.

This comment is a soft signal. The Sonar scan runs on push to main; the PR check itself never fails on smells.

[github-actions]

Review-bot acknowledgement summary

• Must-address findings: 0 (0 acknowledged, 0 open)
• Informational findings: 0

All must-address findings are resolved or acknowledged.

[github-actions]

bernstein doctor observe for PR #2052 (renovate/prom-prometheus-3.x): ok=1, warn=0, fail=1, error=0, skipped=2

sonar -- OK (project bernstein)

metric	value	delta	threshold	status
coverage_pct	80.1%	new	80.0%	ok
code_smells	0	new	50	ok
bugs	0	new	0	ok
vulnerabilities	0	new	0	ok
security_hotspots	0	new	0	ok

code-scanning -- FAIL (36 open alert(s))

metric	value	delta	threshold	status
open_alerts	36	new	0	fail
critical_alerts	1	new	0	fail
high_alerts	15	new	0	fail
medium_alerts	3	new	-	ok
low_alerts	0	new	-	ok

Skipped backends (credentials not configured)

• glitchtip: BERNSTEIN_GLITCHTIP_TOKEN not set
• dt: DTRACK_URL/TOKEN/PROJECT not set

See docs/observability/unified-doctor.md for backend setup notes.