Adding /cargo/bin volume in Podman and README updates

- In version 1.6.3 of Podman, support for anonymous volues was added
  which allows for Docker and Podman to both add /cargo/bin for MacOS
  compatibility. The Docker command was reverted to its original version
  and the minimum version of Podman is now set to 1.6.3.
- Minor updates to the README to indicate that Docker and Podman are both
  supported and one of the must be installed.

README.md

@@ -36,14 +36,18 @@ This project is developed and maintained by the [Tools team][team].
 
 - [rustup](https://rustup.rs/)
 
+- A Linux kernel with [binfmt_misc] support is required for cross testing.
+
+[binfmt_misc]: https://www.kernel.org/doc/html/latest/admin-guide/binfmt-misc.html
+
+One of these container engines is required:
+
 - [Docker](https://www.docker.com/). Note that on Linux non-sudo users need to be in the
   `docker` group. Read the official [post-installation steps][post].
 
 [post]: https://docs.docker.com/install/linux/linux-postinstall/
 
-- A Linux kernel with [binfmt_misc] support is required for cross testing.
-
-[binfmt_misc]: https://www.kernel.org/doc/html/latest/admin-guide/binfmt-misc.html
+- [Podman](https://podman.io). Requires version 1.6.3 or later.
 
 ## Installation
 

src/docker.rs

@@ -146,15 +146,9 @@ pub fn run(target: &Target,
     docker
         .args(&["-e", &format!("CROSS_RUNNER={}", runner.unwrap_or_else(|| String::new()))])
         .args(&["-v", &format!("{}:/xargo:Z", xargo_dir.display())])
-        .args(&["-v", &format!("{}:/cargo:Z", cargo_dir.display())]);
-
-    // Prevent `bin` from being mounted inside the Docker container. This is
-    // not required for Podman.
-    if container_engine == DOCKER {
-        docker.args(&["-v", "/cargo/bin"]);
-    }
-
-    docker
+        .args(&["-v", &format!("{}:/cargo:Z", cargo_dir.display())])
+        // Prevent `bin` from being mounted inside the Docker container.
+        .args(&["-v", "/cargo/bin"])
         .args(&["-v", &format!("{}:/project:Z,ro", root.display())])
         .args(&["-v", &format!("{}:/rust:Z,ro", sysroot.display())])
         .args(&["-v", &format!("{}:/target:Z", target_dir.display())])