grass.gunittest: Use collections.abc for Iterable (#2006)

Python 3.10 does not have Iterable in collections anymore and requires collections.abc.Iterable.

python/grass/gunittest/reporters.py

@@ -17,6 +17,7 @@ import subprocess
 import sys
 import collections
 import re
+from collections.abc import Iterable
 
 from .utils import ensure_dir
 from .checkers import text_to_keyvalue
@@ -36,7 +37,7 @@ def keyvalue_to_text(keyvalue, sep="=", vsep="\n", isep=",", last_vertical=None)
     items = []
     for key, value in keyvalue.items():
         # TODO: use isep for iterables other than strings
-        if not isinstance(value, str) and isinstance(value, collections.Iterable):
+        if not isinstance(value, str) and isinstance(value, Iterable):
             # TODO: this does not work for list of non-strings
             value = isep.join(value)
         items.append("{key}{sep}{value}".format(key=key, sep=sep, value=value))