Add --color=always to test explorer command

Fixes rust-lang/rust-analyzer#20030

Author: joshka

src/tools/rust-analyzer/crates/rust-analyzer/src/test_runner.rs

@@ -103,6 +103,7 @@ impl CargoTestHandle {
     ) -> std::io::Result<Self> {
         let mut cmd = toolchain::command(Tool::Cargo.path(), root, &options.extra_env);
         cmd.env("RUSTC_BOOTSTRAP", "1");
+        cmd.arg("--color=always");
         cmd.arg("test");
 
         cmd.arg("--package");