Add codspeed benchmarks

[bdraco]

We are planning on merging free-threading support in #1015 but have no good way to test this does not regress performance on non free-threaded builds. Add benchmarks ahead of merge so we can get a test in the CI

[codspeed-hq]

CodSpeed Performance Report

Congrats! CodSpeed is installed 🎉

🆕 38 new benchmarks were detected.

You will start to see performance impacts in the reports once the benchmarks are run from your default branch.

Detected benchmarks

• test_cimultidict_add_istr (81.6 µs)
• test_cimultidict_add_str (106.8 µs)
• test_cimultidict_clear_str (14.3 µs)
• test_cimultidict_delitem_istr (113.3 µs)
• test_cimultidict_delitem_str (161 µs)
• test_cimultidict_extend_istr (147.7 µs)
• test_cimultidict_extend_str (187.6 µs)
• test_cimultidict_fetch_istr (61.3 µs)
• test_cimultidict_fetch_str (85.3 µs)
• test_cimultidict_get_hit (117.8 µs)
• test_cimultidict_get_hit_with_default (125.3 µs)
• test_cimultidict_get_istr_hit (94.1 µs)
• test_cimultidict_get_istr_hit_with_default (101.2 µs)
• test_cimultidict_get_istr_miss (152 µs)
• test_cimultidict_get_istr_with_default_miss (159.4 µs)
• test_cimultidict_get_miss (176.9 µs)
• test_cimultidict_get_miss_with_default (185.3 µs)
• test_cimultidict_getall_istr_hit (33.9 µs)
• test_cimultidict_getall_str_hit (41.2 µs)
• test_cimultidict_insert_istr (69.2 µs)
• test_cimultidict_insert_str (100.1 µs)
• test_cimultidict_pop_istr (129.9 µs)
• test_cimultidict_pop_str (177.9 µs)
• test_cimultidict_popitem_str (97.8 µs)
• test_cimultidict_update_istr (157.8 µs)
• test_cimultidict_update_str (184 µs)
• test_multidict_add_str (77.2 µs)
• test_multidict_clear_str (14.3 µs)
• test_multidict_delitem_str (103.6 µs)
• test_multidict_extend_str (186.8 µs)
• test_multidict_fetch (55.7 µs)
• test_multidict_get_hit (87.8 µs)
• test_multidict_get_miss (147 µs)
• test_multidict_getall_str_hit (33.3 µs)
• test_multidict_insert_str (70.3 µs)
• test_multidict_pop_str (120.3 µs)
• test_multidict_popitem_str (97.8 µs)
• test_multidict_update_str (151.3 µs)