native-deps-action fails to locate .so file and tries to check .rb one.

[ni4]

Ubuntu CI run from PR https://github.com/rnpgp/ruby-rnp/pull/79 fails to run with the following messages:

Testing lib/rnp/ffi/librnp.rb ...
    not a dynamic executable
Command ldd "lib/rnp/ffi/librnp.rb" FAILED!

However, .so file should be in place:

mkdir -p pkg/rnp-1.0.4-x86_64-linux/lib/rnp/ffi
rm -f pkg/rnp-1.0.4-x86_64-linux/lib/rnp/ffi/librnp.rb
ln lib/rnp/ffi/librnp.rb pkg/rnp-1.0.4-x86_64-linux/lib/rnp/ffi/librnp.rb
rm -f pkg/rnp-1.0.4-x86_64-linux/lib/rnp/ffi/librnp.so
ln lib/rnp/ffi/librnp.so pkg/rnp-1.0.4-x86_64-linux/lib/rnp/ffi/librnp.so

Here are two problems:

• why .so file is not found, while it is reported as linked correctly
• glob.glob() pattern should be updated to not match librnp.rb