remove trailing whitespace README.md

Signed-off-by: Nathaniel <[email protected]>

Author: NathanielF

README.md

@@ -195,7 +195,7 @@ Propensity scores are often used to address the risks of bias or confounding int
 selection effects into the treatment condition. Propensity scores can be used in a number of ways, but here we demonstrate
 their usage within corrective weighting schemes aimed to recover as-if random allocation of subjects to the treatment condition.
 The technique "up-weights" or "down-weights" individual observations to better estimate a causal estimand such as the average treatment
-effect. 
+effect.
 
 ![](https://raw.githubusercontent.com/pymc-labs/CausalPy/main/docs/source/_static/propensity_weight.png)