deps: libffi-4.1 and others

The updated libffi is needed to fix an issue with MacOS 15, and the fix
has a side-effect of increasing MSRV to 1.78. See
#209

We will stick with bindgen-1.70.1 because bindgen-1.71.1 does not
correctlly identify when to avoid using unsafe extern "C" { ... }, which
was first added in rust-1.82.

rust-lang/rust-bindgen#3015
https://doc.rust-lang.org/edition-guide/rust-2024/unsafe-extern.html

Author: jedbrown

.github/workflows/test.yaml

@@ -28,7 +28,7 @@ jobs:
             mpi_package: libmpich-dev
             cargo_flags: --all-features
           - os: ubuntu-22.04
-            rust: 1.70.0
+            rust: 1.78.0
             mpi_package: libmpich-dev
             cargo_flags: --all-features
           - os: macos-latest

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 ## `main` branch
 
-**MSRV:** 1.70
+**MSRV:** 1.78
 
 ### New Features