refactor: use variable for environment prefix

cmd/server/server.go

@@ -14,14 +14,16 @@ import (
 	"git.brettb.xyz/goinv/server/internal/types"
 )
 
+var envPrefix = "GOINV_SRV_"
+
 func main() {
 	seed := flag.Bool("seed", false, "seed the database")
 	flag.Parse()
 
 	config.LoadConfig(file.Provider("config.json"), json.Parser())
-	config.LoadConfig(env.Provider("GOINV_SRV_", ".", func(s string) string {
+	config.LoadConfig(env.Provider(envPrefix, ".", func(s string) string {
 		return strings.Replace(strings.ToLower(
-			strings.TrimPrefix(s, "GOINV_SRV_")), "_", ".", -1,
+			strings.TrimPrefix(s, envPrefix)), "_", ".", -1,
 		)
 	}), nil)