tests: build: rust: switch from SHA1 to SHA256 for module signing

Root cause is unclear but it seems that attempts to build with SHA1
on Fedora 41 are failing. We need to keep an eye on this for other
build scripts.

Signed-off-by: Jakub Kicinski <[email protected]>

Author: kuba-moo

tests/patch/build_clang_rust/build_clang_rust.sh

@@ -20,6 +20,12 @@ prep_config() {
     # KVM has its own WERROR control, and it currently does generate errors!
     ./scripts/config --file $output_dir/.config -d kvm_werror
 
+    # Unclear if this is related to Rust but we seem to get key generation
+    # issues with SHA1 on Fedora 41. Switch to SHA256.
+    ./scripts/config --file $output_dir/.config -d module_sig_sha1
+    ./scripts/config --file $output_dir/.config -e module_sig_sha256
+    ./scripts/config --file $output_dir/.config --set-str module_sig_hash sha256
+
     # allmodconfig is not sufficient to get Rust support enabled. So
     # flip some options.