PyBytes_Size test for a zero-size bytes object

[nybblista]

test.test_capi.test_bytes.CAPITest.test_size that test PyBytes_Size() does not check for a zero-size bytes object.

Linked PRs

• gh-131339: test PyBytes_Size for a zero-size bytes object #131340
• [3.13] gh-131339: test PyBytes_Size for a zero-size bytes object (GH-131340) #131343
• [3.12] gh-131339: test PyBytes_Size for a zero-size bytes object (GH-131340) #131344