wendelin.core: v↑ 2.0.alpha2.pre1 -> 2.0.alpha2.post1

Finishing touches to release wendelin.core 2.0.alpha2:

- Switch to using File IO provided by Pygolang
- Fix build_dso on clean checkout (not relevant for SlapOS)

wendelin.core@11e023cf...ad6305c0

Tested via:

ERP5: https://nexedijs.erp5.net/#/test_result_module/20220127-586CEAFD
Wendelin: https://nexedijs.erp5.net/#/test_result_module/20220127-8444F82A