update MSRV to 1.81 for base64 dep

Author: Keruspe

.github/workflows/build-and-test.yaml

@@ -13,7 +13,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        rust: [nightly, beta, stable, 1.80.0]
+        rust: [nightly, beta, stable, 1.81.0]
     steps:
       - uses: actions/checkout@v4