fix(da): da test (#2266)

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## Overview

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<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit

- **Tests**
- Updated the namespace value used in the JSONRPC proxy client tests to
use its hexadecimal ASCII representation.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Co-authored-by: tac0turtle <you@example.com>

Author: tac0turtle

da/jsonrpc/proxy_test.go

@@ -46,7 +46,7 @@ func TestProxy(t *testing.T) {
 		}
 	}()
 
-	client, err := proxy.NewClient(context.Background(), logger, ClientURL, "", "test")
+	client, err := proxy.NewClient(context.Background(), logger, ClientURL, "", "74657374")
 	require.NoError(t, err)
 	RunDATestSuite(t, &client.DA)
 }