fix: Update Diamond tier sponsorship price

Author: rodneyosodo

src/app/(articles)/sponsors.mdx

@@ -23,7 +23,7 @@ Join us in shaping the future of Python in Kenya! PyCon KE brings together devel
 
 ## Sponsorship Tiers
 
-### Diamond Tier (KSH 800,000)
+### Diamond Tier (KSH 1,000,000)
 
 - Premium booth placement
 - Keynote speaking opportunity