Try setting the IP for the integration tests (#2000)

# Rationale for this change

The [integration tests started
failing](https://github.com/apache/iceberg-python/commits/main/); this
fixes it, according to Stack Overflow and the CI.

# Are these changes tested?

# Are there any user-facing changes?

<!-- In the case of user-facing changes, please add the changelog label.
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Author: Fokko

tests/conftest.py

@@ -2443,6 +2443,7 @@ def spark() -> "SparkSession":
     os.environ["AWS_REGION"] = "us-east-1"
     os.environ["AWS_ACCESS_KEY_ID"] = "admin"
     os.environ["AWS_SECRET_ACCESS_KEY"] = "password"
+    os.environ["SPARK_LOCAL_IP"] = "127.0.0.1"
 
     spark = (
         SparkSession.builder.appName("PyIceberg integration test")