fix: restore context after block.call

If return is called in the with_context block, the context cannot be restored to its original state.
The "ensure" clause call post-processing even if it called returned in the middle of block.call.

lib/fusuma/config/searcher.rb

@@ -84,6 +84,7 @@ class << self
         def with_context(context, &block)
           @context = context || {}
           result = block.call
+        ensure # NOTE: ensure is called even if return in block
           @context = {}
           result
         end