Fix acceptance/bundle/resources/model_serving_endpoints/running-endpoint test (#3927)

The test was failing because not all cloud environments have a version
"1" available for the model. Expanding the regex check to all integers
should fix the failure.

Failure diff:
```
    acceptance_test.go:807: Diff:
        --- bundle/resources/model_serving_endpoints/running-endpoint/output.txt
        +++ /tmp/TestAcceptbundleresourcesmodel_serving_endpointsrunning-endp4294099973/001/output.txt
        @@ -16,7 +16,7 @@
               "served_entities": [
                 {
                   "entity_name": "system.ai.llama_v3_2_1b_instruct",
        -          "entity_version": "[VERSION]",
        +          "entity_version": "2",
                   "name": "llama",
                   "scale_to_zero_enabled": true,
                   "workload_size": "Small"
```

Co-authored-by: Denis Bilenko <[email protected]>

Author: shreyas-goenka

acceptance/bundle/resources/model_serving_endpoints/running-endpoint/test.toml

@@ -17,5 +17,5 @@ Response.Body = '''
 '''
 
 [[Repls]]
-Old = '"entity_version": "1",'
+Old = '"entity_version": "\d+",'
 New = '"entity_version": "[VERSION]",'