Update cortex-m-rt

Author: Sh3Rm4n

Cargo.toml

@@ -36,7 +36,7 @@ rustc-args = ["--cfg", "docsrs"]
 [dependencies]
 cfg-if = "1.0.0"
 cortex-m = "0.7.4"
-cortex-m-rt = "0.7"
+cortex-m-rt = "0.7.3"
 defmt = { version = ">=0.2.3, <0.4.0", optional = true }
 embedded-dma = "0.2.0"
 embedded-hal = { version = "0.2.5", features = ["unproven"] }
@@ -72,7 +72,7 @@ rtt-target = { version = "0.3.1", features = ["cortex-m"] }
 slice-group-by = "0.3.0"
 
 [features]
-default = ["rt", "ld", "usb", "can", "rtc", "enumset"]
+default = ["rt", "ld", "usb", "can", "rtc", "enumset", "cortex-m/critical-section-single-core"]
 device-selected = []
 direct-call-deprecated = []
 ld = []