refactor: Replace all uses of boost::optional with our own Optional type

After this:

- `boost::optional` is no longer used directly (only through `Optional`
    which is an alias for it)
- `boost/optional.hpp` is only included in one place

1 files changed, 1 insertions, 1 deletions

diff --git a/src/psbt.h b/src/psbt.h
index 802a7c5ba7..9d996171bb 100644
--- a/src/psbt.h
+++ b/src/psbt.h
@@ -387,7 +387,7 @@ struct PSBTOutput
 /** A version of CTransaction with the PSBT format*/
 struct PartiallySignedTransaction
 {
-    boost::optional<CMutableTransaction> tx;
+    Optional<CMutableTransaction> tx;
     std::vector<PSBTInput> inputs;
     std::vector<PSBTOutput> outputs;
     std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;