v0.83.3

• [Feature]: Accept functions as arguments to mergeConfig. (#1580 by @robhogan)
• [Fix]: Fix regression loading config files that export a promise. (#1586 by @robhogan)
• [Fix]: Don't obscure errors parsing/evaluating metro.config.js. (af3bcca by @robhogan)
• [Fix]: Fix mergeConfig handling of 2+ partial configs. (a99067f by @robhogan)

Full Changelog: v0.83.2...v0.83.3