python-pyrsistent: bump to 0.20.0

Changelog: https://github.com/tobgu/pyrsistent/blob/master/CHANGES.txt
Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>

lang/python/python-pyrsistent/test.sh

@@ -0,0 +1,29 @@
+#!/bin/sh
+
+[ "$1" = python3-pyrsistent ] || exit 0
+
+python3 - << 'EOF'
+
+from pyrsistent import pmap, pvector, pset
+
+# Persistent map
+m = pmap({"a": 1, "b": 2})
+m2 = m.set("c", 3)
+assert m["a"] == 1
+assert "c" not in m
+assert m2["c"] == 3
+
+# Persistent vector
+v = pvector([1, 2, 3])
+v2 = v.append(4)
+assert len(v) == 3
+assert len(v2) == 4
+assert v2[3] == 4
+
+# Persistent set
+s = pset([1, 2, 3])
+s2 = s.add(4)
+assert 4 not in s
+assert 4 in s2
+
+EOF