Bump MSRV to 1.77 to support C-string literals

Author: Sympatron

.github/workflows/build.yml

@@ -103,7 +103,7 @@ jobs:
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
-          toolchain: 1.75.0 # clippy is too much of a moving target at the moment
+          toolchain: 1.77.0 # clippy is too much of a moving target at the moment
           override: true
           components: clippy
       - uses: actions-rs/clippy-check@v1