Update integration-with-fastify.mdx for fastify v5

[Fenykepy]

Upgraded doc to work with Fastify v5, according to this issue:
#3763

[changeset-bot]

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Latest commit: 3dce9a3

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[ardatan]

Thanks 🙏

[github-actions]

✅ Benchmark Results

     ✓ no_errors{mode:graphql}
     ✓ expected_result{mode:graphql}
     ✓ no_errors{mode:graphql-jit}
     ✓ expected_result{mode:graphql-jit}
     ✓ no_errors{mode:graphql-response-cache}
     ✓ expected_result{mode:graphql-response-cache}
     ✓ no_errors{mode:graphql-no-parse-validate-cache}
     ✓ expected_result{mode:graphql-no-parse-validate-cache}
     ✓ no_errors{mode:uws}
     ✓ expected_result{mode:uws}

     checks.......................................: 100.00% ✓ 520154      ✗ 0     
     data_received................................: 2.1 GB  14 MB/s
     data_sent....................................: 105 MB  697 kB/s
     http_req_blocked.............................: avg=1.51µs   min=971ns    med=1.33µs   max=324.09µs p(90)=1.96µs   p(95)=2.16µs  
     http_req_connecting..........................: avg=2ns      min=0s       med=0s       max=135.38µs p(90)=0s       p(95)=0s      
     http_req_duration............................: avg=358.54µs min=213.91µs med=328.23µs max=18.64ms  p(90)=469.97µs p(95)=491.59µs
       { expected_response:true }.................: avg=358.54µs min=213.91µs med=328.23µs max=18.64ms  p(90)=469.97µs p(95)=491.59µs
     ✓ { mode:graphql-jit }.......................: avg=283.61µs min=213.91µs med=267.73µs max=18.64ms  p(90)=297.15µs p(95)=309.11µs
     ✓ { mode:graphql-no-parse-validate-cache }...: avg=494.99µs min=408.33µs med=472.41µs max=7.83ms   p(90)=514.11µs p(95)=565.55µs
     ✓ { mode:graphql-response-cache }............: avg=345.14µs min=270.82µs med=328.92µs max=6.54ms   p(90)=358.44µs p(95)=368.93µs
     ✓ { mode:graphql }...........................: avg=363.38µs min=278.29µs med=337.65µs max=14.06ms  p(90)=383.16µs p(95)=424.67µs
     ✓ { mode:uws }...............................: avg=344.47µs min=264.9µs  med=326.97µs max=6.44ms   p(90)=360.78µs p(95)=381.16µs
     http_req_failed..............................: 0.00%   ✓ 0           ✗ 260077
     http_req_receiving...........................: avg=32.93µs  min=16.69µs  med=32.49µs  max=5.88ms   p(90)=39.25µs  p(95)=41.77µs 
     http_req_sending.............................: avg=8.69µs   min=5.96µs   med=7.62µs   max=333.31µs p(90)=11.05µs  p(95)=12.19µs 
     http_req_tls_handshaking.....................: avg=0s       min=0s       med=0s       max=0s       p(90)=0s       p(95)=0s      
     http_req_waiting.............................: avg=316.92µs min=181.36µs med=287.58µs max=18.52ms  p(90)=427.72µs p(95)=447.84µs
     http_reqs....................................: 260077  1733.828876/s
     iteration_duration...........................: avg=571.72µs min=388.84µs med=537.14µs max=19.18ms  p(90)=686.58µs p(95)=712.57µs
     iterations...................................: 260077  1733.828876/s
     vus..........................................: 1       min=1         max=1   
     vus_max......................................: 2       min=2         max=2