Bump pyrsistent from 0.15.0 to 0.15.1 (#4915)

Bumps [pyrsistent](https://github.com/tobgu/pyrsistent) from 0.15.0 to 0.15.1.
- [Release notes](https://github.com/tobgu/pyrsistent/releases)
- [Changelog](https://github.com/tobgu/pyrsistent/blob/master/CHANGES.txt)
- [Commits](https://github.com/tobgu/pyrsistent/compare/v0.15.0...v0.15.1)

Signed-off-by: dependabot[bot] <support@dependabot.com>

requirements/common.txt

@@ -331,5 +331,5 @@ first==2.0.2 \
 attrs==19.1.0 \
     --hash=sha256:69c0dbf2ed392de1cb5ec704444b08a5ef81680a61cb899dc08127123af36a79 \
     --hash=sha256:f0b870f674851ecbfbbbd364d6b5cbdff9dcedbc7f3f5e18a6891057f21fe399
-pyrsistent==0.15.0 \
-    --hash=sha256:b254ba347831270a2cb349386680863732b89fc79be4d1141daff1c11196ccc5
+pyrsistent==0.15.1 \
+    --hash=sha256:5403d37f4d55ff4572b5b5676890589f367a9569529c6f728c11046c4ea4272b