Memory usage goes up rapidly after resizing window

Hello,

After I resize a window created by RLTK, the process begins to use up more memory, and the memory doesn't seem to ever go back down. It doesn't really matter if I shake the window around or slightly adjust the size as a regular user would, the memory still goes up. I've attached a .gif which shows this behavior.

How to reproduce:

main.rs:
```rust
use rltk::{GameState, Rltk, RltkBuilder};
struct State {}

impl GameState for State {
fn tick(&mut self, ctx: &mut Rltk) {
ctx.print(1, 1, "Hello world!");
}
}

fn main() -> rltk::BError {
let game_state = State {};

let context = RltkBuilder::simple80x50().with_title(" ").build()?;
rltk::main_loop(context, game_state)
}
```

Cargo.toml:
```toml
[package]
name = "roguelike"
version = "0.1.0"
edition = "2021"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[dependencies]
rltk = { version = "0.8.0" }
```

My system information:

Operating System: Artix Linux
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3
Kernel Version: 5.16.16-artix1-1 (64-bit)
Graphics Platform: X11
Processors: 6 × Intel® Core™ i5-9400F CPU @ 2.90GHz
Memory: 15.5 GiB of RAM
Graphics Processor: NVIDIA GeForce GTX 1660 SUPER/PCIe/SSE2
Rustc Version: rustc 1.59.0 (9d1b2106e 2022-02-23)
Cargo Version: cargo 1.59.0 (49d8809dc 2022-02-10)