chore: add `PAYMASTER_SIGNER_KEY` to `.env.example`

chore: add PAYMASTER_SIGNER_KEY to .env.example

diff --git a/.env.example b/.env.example
index 5b8feaf..c7eab5b 100644
--- a/.env.example
+++ b/.env.example
@@ -1 +1,2 @@
-THIRDWEB_API_KEY=
\ No newline at end of file
+THIRDWEB_API_KEY=
+PAYMASTER_SIGNER_KEY=
\ No newline at end of file

GitHub
sha: 941c399c67edb859dd4928234673241d577f91dd