player: add timeout when fetching song metadata

[cosven]

Currently, the player play the media after metadata is fetched.
However, some provider (ytmusic) cost much time in fetching metadata.
So add a timeout to workaround this problem.

[coveralls]

Pull Request Test Coverage Report for Build 9827709781

Details

• 8 of 13 (61.54%) changed or added relevant lines in 3 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.04%) to 55.062%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
feeluown/library/library.py	0	5	0.0%

Files with Coverage Reduction	New Missed Lines	%
feeluown/library/library.py	5	66.15%

Totals
Change from base Build 9732123954:	-0.04%
Covered Lines:	9849
Relevant Lines:	17887

---

💛 - Coveralls