Update pipeline image

Author: kabilar

README.md

@@ -12,7 +12,7 @@ Presently, the primary developer of DataJoint open-source software is the compan
 
 ## Data Pipeline Example
 
-![pipeline](https://raw.githubusercontent.com/datajoint/datajoint-python/master/images/pipeline.jpg)
+![pipeline](https://raw.githubusercontent.com/datajoint/datajoint-python/master/images/pipeline.png)
 
 [Yatsenko et al., bioRxiv 2021](https://doi.org/10.1101/2021.03.30.437358)
 

docs/src/index.md

@@ -7,7 +7,7 @@ Presently, the primary developer of DataJoint open-source software is the compan
 
 ## Data Pipeline Example
 
-![pipeline](https://raw.githubusercontent.com/datajoint/datajoint-python/master/images/pipeline.jpg)
+![pipeline](https://raw.githubusercontent.com/datajoint/datajoint-python/master/images/pipeline.png)
 
 [Yatsenko et al., bioRxiv 2021](https://doi.org/10.1101/2021.03.30.437358){:target="_blank"}