[CI] Install cspell/dict before running cspell action

[chalin]

• Contributes to Fix spell check to detect Spanish spelling errors #5007

[chalin]

Woohoo, spell checking is working now for non-en languages, see https://github.com/open-telemetry/opentelemetry.io/actions/runs/10319248972/job/28567258019?pr=5008:

Run streetsidesoftware/cspell-action@v6
cspell-action
Pull Request
Warning: Unknown word (Telemetría) Suggestions: (telemetria, telemetric, telemetrias, telemétrica, telemetry)
content/es/_index.md:4:3 Unknown word (Telemetría) Suggestions: (telemetria, telemetric, telemetrias, telemétrica, telemetry)
content/es/_index.md:4:59 Unknown word (observabilidad) Suggestions: (observabilidade, observabilidades, observability, obsedabilidade, obsediabilidade)
content/es/_index.md:48:54 Unknown word (telemetría) Suggestions: (telemetria, telemetric, telemetrias, telemétrica, telemetry)
content/es/_index.md:62:28 Unknown word (telemetría) Suggestions: (telemetria, telemetric, telemetrias, telemétrica, telemetry)
content/es/_index.md:63:1 Unknown word (reenvíalos) Suggestions: (reenvia-os, reenviados, reenviamos, reenviarlos, reenviá-los)
content/es/_index.md:80:60 Unknown word (observabilidad) Suggestions: (observabilidade, observabilidades, observability, obsedabilidade, obsediabilidade)

/cc @theletterf

[theletterf]

Yay!

[chalin]

Merging now so that we can test the functionality over #5009.