Update gcc and gxx dependencies in environment.yml to fix GitHub Actions

Removed specific version numbers for gcc and gxx.

Author: pkawak

environment.yml

@@ -3,8 +3,8 @@ channels:
   - conda-forge
 dependencies:
   # toolchain
-  - gcc_linux-64=11.2.0
-  - gxx_linux-64=11.2.0
+  - gcc_linux-64
+  - gxx_linux-64
   - kernel-headers_linux-64=3.10.0
   - sysroot_linux-64=2.17
   # build tools