feat: Configurable Connect/Read Timeouts

[tylerjroach]

Add custom connect and read timeout support

Adds the ability to configure custom connect and read timeouts for network requests via the MixpanelAPI.Builder.

Changes

• Added connectTimeout(int) and readTimeout(int) methods to MixpanelAPI.Builder
• Default timeouts remain unchanged (2s connect, 10s read)
• Setting 0 allows indefinite timeout; negative values are ignored

Usage

MixpanelAPI api = new MixpanelAPI.Builder()
    .connectTimeout(5000)  // 5 seconds
    .readTimeout(30000)    // 30 seconds
    .build();

[jaredmixpanel]

LGTM