Change pineappl version to 0.5.6

Author: andreab1997

poetry.lock

@@ -25,7 +25,7 @@ packages = [{ include = "pineko", from = "src" }]
 [tool.poetry.dependencies]
 python = ">=3.8,<3.11"
 eko = "^0.10.2"
-pineappl = "^0.5.5"
+pineappl = "^0.5.6"
 PyYAML = "^6.0"
 numpy = "^1.21.0"
 pandas = "^1.4.1"