Update GSF web banner to point to Decarb reg website

[zanete]

Scope of work:

• change the CTA to be "Register Now"
• change the text to be TBC
• change the logo to the Decarbonize logo

[zanete]

@NAMRATA-WOKE please suggest the copy for the banner so that it can be updated before the event in Spain

[zanete]

@NAMRATA-WOKE ping to remind 🙏

[NAMRATA-WOKE]

Thanks for the ping @zanete. Language:

Join Decarbonize Software on November 16. [Register Now]

[zanete]

@osamajandali this is now ready for you, thanks!