Add output_changed_message!, replace some .expects (#1110)

src/utils.rs

@@ -282,3 +282,15 @@ pub fn install_color_eyre() -> Result<()> {
         .display_location_section(true)
         .install()
 }
+
+/// Macro to construct an error message for when the output of a command is unexpected.
+#[macro_export]
+macro_rules! output_changed_message {
+    ($command:expr, $message:expr) => {
+        format!(
+            "The output of `{}` changed: {}. This is not your fault, this is an issue in Topgrade. Please open an issue at: https://github.com/topgrade-rs/topgrade/issues/new?template=bug_report.md",
+            $command,
+            $message,
+        )
+    };
+}