Revise ui test.

tests/ui/single_component_use_path.fixed

@@ -1,10 +1,10 @@
 // run-rustfix
-// compile-flags: --edition 2018
 #![warn(clippy::single_component_use_path)]
 
+extern crate semver;
 
 
 fn main() {
-    let escaped = std::ascii::escape_default(b'\t');
-    println!("{}", escaped);
+    let version = semver::Version::parse("1.2.3").unwrap();
+    println!("Version: {}", version);
 }

tests/ui/single_component_use_path.rs

@@ -2,9 +2,10 @@
 // compile-flags: --edition 2018
 #![warn(clippy::single_component_use_path)]
 
-use std;
+extern crate semver;
+use semver;
 
 fn main() {
-    let escaped = std::ascii::escape_default(b'\t');
-    println!("{}", escaped);
+    let version = semver::Version::parse("1.2.3").unwrap();
+    println!("Version: {}", version);
 }

tests/ui/single_component_use_path.stderr

@@ -1,10 +1,21 @@
-error: this import is redundant in 2018 edition
+error[E0254]: the name `semver` is defined multiple times
+  --> $DIR/single_component_use_path.rs:5:5
+   |
+LL | extern crate semver;
+   | -------------------- previous import of the extern crate `semver` here
+LL | use semver;
+   |     ^^^^^^ `semver` reimported here
+   |
+   = note: `semver` must be defined only once in the type namespace of this module
+
+error: this import is redundant
   --> $DIR/single_component_use_path.rs:5:1
    |
-LL | use std;
-   | ^^^^^^^^ help: remove it entirely
+LL | use semver;
+   | ^^^^^^^^^^^ help: remove it entirely
    |
    = note: `-D clippy::single-component-use-path` implied by `-D warnings`
 
-error: aborting due to previous error
+error: aborting due to 2 previous errors
 
+For more information about this error, try `rustc --explain E0254`.