Adjust WasmThemis 0.13.11 release date
Gotta pad my commit stats, okay?
Changes that are currently in development and have not been released yet.
-## [0.13.11](https://github.com/cossacklabs/themis/releases/tag/0.13.11), June 30th 2021
+## [0.13.11](https://github.com/cossacklabs/themis/releases/tag/0.13.11), July 6th 2021
**Hotfix for WasmThemis:**
