Pin embedded-hal to 1.0.0-rc.1

embedded-hal 1.0.0-rc.2 introduces backwards incompatible changes.  This change pins the crate to 1.0.0-rc.1.

riscv/Cargo.toml

@@ -24,4 +24,4 @@ critical-section-single-hart = ["critical-section/restore-state-bool"]
 
 [dependencies]
 critical-section = "1.1.2"
-embedded-hal = "1.0.0-rc.1"
+embedded-hal = "=1.0.0-rc.1"