Update stm32l4xx-hal requirement in /rtic_v0.5/stm32l4_heartbeat

Updates the requirements on [stm32l4xx-hal](https://github.com/MabezDev/stm32l4xx-hal) to permit the latest version.
- [Release notes](https://github.com/MabezDev/stm32l4xx-hal/releases)
- [Changelog](https://github.com/stm32-rs/stm32l4xx-hal/blob/master/CHANGELOG.md)
- [Commits](stm32-rs/stm32l4xx-hal@v0.5.0...v0.6.0)

---
updated-dependencies:
- dependency-name: stm32l4xx-hal
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

rtic_v0.5/stm32l4_heartbeat/Cargo.lock

@@ -12,8 +12,8 @@ edition = "2018"
 panic-semihosting = "0.6"
 cortex-m-semihosting = "0.5.0"
 embedded-hal = "0.2.3"
-cortex-m-rtic = "0.5.1"
-stm32l4xx-hal = { version = "0.5.0", features = ["rt", "stm32l4x2"] }
+cortex-m-rtic = { version = "0.5.9", default-features = false, features = ["cortex-m-7"] }
+stm32l4xx-hal = { version = "0.6.0", features = ["rt", "stm32l4x2"] }
 heapless = "0.7.16"
 
 # this lets you use `cargo fix`!

rtic_v0.5/stm32l4_heartbeat/Cargo.toml

@@ -38,7 +38,11 @@ const APP: () = {
         // Setup clocks
         let mut flash = cx.device.FLASH.constrain();
         let mut rcc = cx.device.RCC.constrain();
-        let _clocks = rcc.cfgr.sysclk(CLK_SPEED_MHZ.mhz()).freeze(&mut flash.acr);
+        let mut pwr = cx.device.PWR.constrain(&mut rcc.apb1r1);
+        let _clocks = rcc
+            .cfgr
+            .sysclk(CLK_SPEED_MHZ.mhz())
+            .freeze(&mut flash.acr, &mut pwr);
 
         // Setup LED
         let mut gpiob = cx.device.GPIOB.split(&mut rcc.ahb2);