github/workflows: print clippy output in case of errors

In the `unsafe-check` job, if `cargo clippy` fails, we don't have any
log since we are redirecting the stderr to a file to count the number
of undocumented unsafe blocks.

We don't expect it to fail, since other steps in `check` job should
check this case, but it has happened in some cases.

Print the file content in case of `cargo clippy` returns with error,
so we can debug better CI failures.

Reported-by: Oliver Steffen <osteffen@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>

.github/workflows/rust.yml

@@ -149,7 +149,7 @@ jobs:
 
       - name: Clippy with undocumented_unsafe_blocks for PR branch
         run: |
-          cargo clippy --workspace --all-features --exclude packit --exclude stage1 --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure --quiet -- -W clippy::undocumented_unsafe_blocks 2> clippy_warnings_pr.txt
+          cargo clippy --workspace --all-features --exclude packit --exclude stage1 --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure --quiet -- -W clippy::undocumented_unsafe_blocks 2> clippy_warnings_pr.txt || cat clippy_warnings_pr.txt
 
       # Required because after the next checkout everything is removed.
       - name: Upload PR warnings artifact
@@ -169,7 +169,7 @@ jobs:
 
       - name: Clippy with undocumented_unsafe_blocks for base branch
         run: |
-          cargo clippy --workspace --all-features --exclude packit --exclude stage1 --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure --quiet -- -W clippy::undocumented_unsafe_blocks 2> clippy_warnings_base.txt
+          cargo clippy --workspace --all-features --exclude packit --exclude stage1 --exclude svsm-fuzz --exclude igvmbuilder --exclude igvmmeasure --quiet -- -W clippy::undocumented_unsafe_blocks 2> clippy_warnings_base.txt || cat clippy_warnings_base.txt
 
       - name: Download PR warnings artifact
         uses: actions/download-artifact@v4