Example in examples/example_push.rs does not compile

[saleemjaffer]

Describe the bug
The code in examples/example_push.rs does not compile

To Reproduce
Run the code in examples/example_push.rs. I ran it using cargo run --features="push"

This is the error I get:

error[E0425]: cannot find function `push_metrics` in crate `prometheus`
  --> src/main.rs:39:21
   |
39 |         prometheus::push_metrics(
   |                     ^^^^^^^^^^^^ not found in `prometheus`

error[E0422]: cannot find struct, variant or union type `BasicAuthentication` in crate `prometheus`
  --> src/main.rs:44:30
   |
44 |             Some(prometheus::BasicAuthentication {
   |                              ^^^^^^^^^^^^^^^^^^^ not found in `prometheus`

Expected behavior
The code should run fine.

System information

• CPU architecture: 2.6 GHz 6-Core Intel Core i7, MacOS Monterey