use `dyn` in main method declaration

Cargo.lock

@@ -60,7 +60,7 @@ dependencies = [
 
 [[package]]
 name = "in2qr"
-version = "0.1.0"
+version = "1.0.1"
 dependencies = [
  "qr2term",
 ]

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "in2qr"
-version = "1.0.0"
+version = "1.0.1"
 authors = ["Michael Pfaff <michael@pfaff.dev>"]
 edition = "2018"
 

src/main.rs

@@ -1,6 +1,6 @@
 use std::io::prelude::*;
 
-fn main() -> Result<(), Box<std::error::Error>> {
+fn main() -> Result<(), Box<dyn std::error::Error>> {
     let stdin = std::io::stdin();
     let mut stdin = stdin.lock();
     let mut buffer = Vec::new();