Relax lint message string comparison

This will allow to check that certain reasonable parts of the message are present without expecting an exact match.

This is useful, when the warning or error messages slightly differ from version to version.

lib/galaxy/tool_util/lint.py

@@ -83,10 +83,13 @@ def __init__(self, level: str, message: str, **kwargs):
     def __eq__(self, other) -> bool:
         """
         add equal operator to easy lookup of a message in a
-        List[LintMessage] which is usefull in tests
+        List[LintMessage] which is useful in tests.
+
+        If the other object is a string, it is loosely checked if the
+        string is contained in the message.
         """
         if isinstance(other, str):
-            return self.message == other
+            return other in self.message
         if isinstance(other, LintMessage):
             return self.message == other.message
         return False

test/unit/tool_util/test_tool_linters.py

@@ -1391,10 +1391,7 @@ def test_inputs_validator_incompatibilities(lint_ctx):
         "Parameter [param_name]: '[' is no valid regular expression: unterminated character set at position 0"
         in lint_ctx.error_messages
     )
-    assert (
-        "Parameter [param_name]: '(' is no valid regular expression: unexpected EOF while parsing (<unknown>, line 1)"
-        in lint_ctx.error_messages
-    )
+    assert "Parameter [param_name]: '(' is no valid regular expression" in lint_ctx.error_messages
     assert (
         "Parameter [another_param_name]: 'metadata' validators need to define the 'check' or 'skip' attribute(s)"
         in lint_ctx.error_messages