Make windows compile (#1035)

Minimal changes to make `cargo check`/`cargo run` work to unblock the
remaining PR stacking

crates/puffin-interpreter/src/interpreter.rs

@@ -127,8 +127,8 @@ impl Interpreter {
 
         #[cfg(windows)]
         {
-            if let Some(python_version) = python_version {
-                compile_error!("Implement me")
+            if let Some(_python_version) = python_version {
+                unimplemented!("Implement me")
             }
 
             let executable = which::which("python.exe")

crates/puffin-interpreter/src/virtual_env.rs

@@ -51,10 +51,7 @@ impl Virtualenv {
         }
         #[cfg(windows)]
         {
-            self.0
-                .join("Scripts")
-                .join("python.exe")
-                .into_std_path_buf()
+            self.root.join("Scripts").join("python.exe")
         }
         #[cfg(not(any(unix, windows)))]
         {