core: allow mermaid node labels to have any characters (#21385)

- it's only node ids that are limited

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libs/core/langchain_core/runnables/graph_mermaid.py

@@ -57,7 +57,7 @@ def draw_mermaid(
         # Add nodes to the graph
         for node in nodes.values():
             node_label = format_dict.get(node, format_dict[default_class_label]).format(
-                _escape_node_label(node), _escape_node_label(node.split(":", 1)[-1])
+                _escape_node_label(node), node.split(":", 1)[-1]
             )
             mermaid_graph += f"\t{node_label};\n"
 

libs/core/tests/unit_tests/runnables/__snapshots__/test_graph.ambr

@@ -122,7 +122,7 @@
   	PromptInput[PromptInput]:::startclass;
   	PromptTemplate([PromptTemplate]):::otherclass;
   	FakeListLLM([FakeListLLM]):::otherclass;
-  	Parallel_as_list_as_str_Input([Parallel_as_list_as_str_Input]):::otherclass;
+  	Parallel_as_list_as_str_Input([Parallel<as_list,as_str>Input]):::otherclass;
   	Parallel_as_list_as_str_Output[Parallel_as_list_as_str_Output]:::endclass;
   	CommaSeparatedListOutputParser([CommaSeparatedListOutputParser]):::otherclass;
   	conditional_str_parser_input([conditional_str_parser_input]):::otherclass;