style: format code with Go fmt and Gofumpt (#2)

This commit fixes the style issues introduced in 26763b1 according to the output
from Go fmt and Gofumpt.

Details: None

Co-authored-by: deepsource-autofix[bot] <62050782+deepsource-autofix[bot]@users.noreply.github.com>

main.go

@@ -212,7 +212,7 @@ var (
 	checksFile        = getEnv("CHECKS_FILE", "checks.yaml")
 	incidentsFile     = getEnv("INCIDENTS_FILE", "incidents.html")
 	historyFile       = getEnv("STATUS_HISTORY_FILE", "history.json")
-	port 		  = getEnv("PORT", "")
+	port              = getEnv("PORT", "")
 )
 
 func getEnv(key, fallback string) string {