fix: Add mising events_uri type to options (#133)

**Requirements**

- [x] I have added test coverage for new or changed functionality
- [x] I have followed the repository's [pull request submission
guidelines](../blob/main/CONTRIBUTING.md#submitting-pull-requests)
- [x] I have validated my changes against all supported platform
versions

**Related issues**

**Describe the solution you've provided**

Add missing type which causing a static analyzer (dialyzer) error when
calling the lib from elixir.

**Describe alternatives you've considered**


**Additional context**

Author: trod

src/ldclient_instance.erl

@@ -17,6 +17,7 @@
     base_uri => string(),
     stream_uri => string(),
     feature_store => atom(),
+    events_uri => string(),
     events_capacity => pos_integer(),
     events_flush_interval => pos_integer(),
     events_dispatcher => atom(),