chore(v4.15.x): release 4.15.7

[shaka-bot]

🤖 I have created a release beep boop

4.15.7 (2025-07-15)

Bug Fixes

• Allow preload segments when we discard the reference by cross boundary logic (#8862) (1c1bffe)
• DASH: Change start number for SubNumber templating, based on DASH 6th edition (#8860) (8c6f41b), closes #8859
• DASH: Update timeline on PTO change (#8869) (6850b43)
• Fix selectAudioTrack when using src= (#8857) (996cdd8)
• Fix Tizen 3 default cross-boundary strategy (#8850) (d5aa1e0)
• Live to VOD discards the wrong segments when crossBoundaryStrategy is not KEEP (#8863) (6664fef)
• UI: Exit from Fullscreen and PiP when unloading (#8848) (86ce3ee)

Performance Improvements

• DRM: Run expiration timer only when EME is in use (#8853) (0568e61)

---

This PR was generated with Release Please. See documentation.

[avelad]

@shaka-bot test

[shaka-bot]

@avelad: Lab tests started with arguments:

• pr=8872

[shaka-bot]

Incremental code coverage: 100.00%

[shaka-bot]

🤖 Created releases:

• v4.15.7

🌻