Update PAC to version 0.12

Author: teskje

Cargo.toml

@@ -23,7 +23,7 @@ embedded-dma = "0.1"
 embedded-hal = "0.2"
 nb = "0.1"
 paste = "1"
-stm32f3 = "0.11"
+stm32f3 = "0.12"
 rtcc = "0.2"
 
 [dependencies.bare-metal]