[chore] Replace blocking Floc with Topics. (#1068)

Google abandoned Floc in favour of Topics and changed the
necessary permissions policy. Currently, the Floc policy will
block Topics. This change includes switching to the updated
policy to be ahead of Google abandoning recognising the Floc
policy.

Update the function documentation to include the current relevant
documentation.

internal/api/security/flocblock.go

@@ -21,8 +21,11 @@ package security
 import "github.com/gin-gonic/gin"
 
 // FlocBlock is a middleware that prevents google chrome cohort tracking by
-// writing the Permissions-Policy header after all other parts of the request have been completed.
-// See: https://plausible.io/blog/google-floc
+// writing the Permissions-Policy header after all other parts of the request
+// have been completed. Floc was replaced by Topics in 2022 and the spec says
+// that interest-cohort will also block Topics (as of 2022-Nov).
+// See: https://smartframe.io/blog/google-topics-api-everything-you-need-to-know
+// See: https://github.com/patcg-individual-drafts/topics
 func (m *Module) FlocBlock(c *gin.Context) {
-	c.Header("Permissions-Policy", "interest-cohort=()")
+	c.Header("Permissions-Policy", "browsing-topics=()")
 }