use env_logger in all examples (#2934)

examples/screenshot/Cargo.toml

@@ -16,5 +16,6 @@ eframe = { path = "../../crates/eframe", features = [
     "__screenshot", # __screenshot is so we can dump a screenshot using EFRAME_SCREENSHOT_TO
     "wgpu",
 ] }
+env_logger = "0.10"
 itertools = "0.10.3"
 image = { version = "0.24", default-features = false, features = ["png"] }

examples/screenshot/src/main.rs

@@ -3,6 +3,7 @@
 use eframe::egui::{self, ColorImage};
 
 fn main() -> Result<(), eframe::Error> {
+    env_logger::init(); // Log to stderr (if you run with `RUST_LOG=debug`).
     let options = eframe::NativeOptions {
         renderer: eframe::Renderer::Wgpu,
         ..Default::default()