Update opus.dll to 1.5.2

[gcask]

Noticed the opus DLL was over 8 years old.

Bringing it into the present.

Built with CMake, default settings, MSVC v143.

[gcask]

Near as can tell, the current version is at best 1.1.3 from july 2016 (commit c7eeaff is from october 2016).

Major releases since then:

• 1.2, july 2017
• 1.3, october 2018
• 1.4, april 2023
• 1.5, march 2024.

(not to mention numerous bugfixes, stability, etc for patch versions).

The fixes are mostly about quality improvements, better handling of speech at low bitrates, error detection, encode/decode optimizations, etc, etc.

Tested with this library while connected on Grayflag, no issues to report - I could hear folks using the old DLL, and they could hear me.

[ciribob]

I'd guess it's around then as that was the first version.

I'd not even thought to update so thanks for this!