[enh] #414: Stop using Poetry lock file

Git ignore poetry.lock
In particular to free pytest version which adds support for Py3.10

.gitignore

@@ -66,3 +66,7 @@ target/
 *~
 *.swp
 *.swo
+
+# Poetry
+# https://python-poetry.org/docs/libraries/#lock-file
+poetry.lock