Unswallow Gem::Package::FormatError

This error happen in a CI run, and as it is currently, it doesn't give
any useful information about the underlying cause. Let's not swallow the
original error.

bundler/lib/bundler/rubygems_integration.rb

@@ -251,8 +251,6 @@ def spec_from_gem(path, policy = nil)
       require "rubygems/security"
       require_relative "psyched_yaml"
       gem_from_path(path, security_policies[policy]).spec
-    rescue Gem::Package::FormatError
-      raise GemspecError, "Could not read gem at #{path}. It may be corrupted."
     rescue Exception, Gem::Exception, Gem::Security::Exception => e # rubocop:disable Lint/RescueException
       if e.is_a?(Gem::Security::Exception) ||
           e.message =~ /unknown trust policy|unsigned gem/i ||