Remove link to Windows 32 bits release

Binaries created with MinGW (even a simple Hello World) are detected as
malware by some anti-virus. For some reason, only the 32 bits version of
scrcpy is impacted.

Since users should use the 64 bits version by default anyway, remove the
link to the 32 bits version from the main page.

The 32 bits release is still available in the "releases" tab.

See <https://github.com/Genymobile/scrcpy/issues/1102>