stack/slapos: version up pyrsistent 0.18.1 (on python3 only)

This removes the need for pytest-testrunner and silent warnings about
its vulnerability in software check

stack/slapos.cfg

@@ -91,6 +91,7 @@ depends = ${slapos-cookbook-dependencies:eggs}
 [pyrsistent]
 recipe = zc.recipe.egg:custom
 egg = pyrsistent
+[pyrsistent:python2]
 setup-eggs = pytest-runner
 
 [slapos-cookbook-dependencies]
@@ -232,7 +233,7 @@ erp5.util = 0.4.74
 feedparser = 5.2.1
 functools32 = 3.2.3.post2
 attrs = 22.1.0
-pyrsistent = 0.16.1
+pyrsistent = 0.18.1
 pytest-runner = 5.2:whl
 ipaddress = 1.0.23
 jsonschema = 3.0.2:whl
@@ -265,6 +266,7 @@ requests = 2.27.1
 charset-normalizer = 2.0.12
 pyparsing = 2.2.0
 certifi = 2020.4.5.1
+pyrsistent = 0.16.1
 
 [versions:sys.version_info < (3,8)]
 MarkupSafe = 1.0