ci: fix rust target triple for riscv64 (riscv64gc-unknown-linux-gnu)

Signed-off-by: Bruno Verachten <gounthar@gmail.com>

Author: gounthar

.github/workflows/main.yml

@@ -30,7 +30,7 @@ jobs:
 
           - artifact: riscv64-linux
             os: ubuntu-24.04
-            rust_target: riscv64-unknown-linux-gnu
+            rust_target: riscv64gc-unknown-linux-gnu
             cross_cmake_args: >-
               -DCMAKE_SYSTEM_NAME=Linux
               -DCMAKE_SYSTEM_PROCESSOR=riscv64