docs: sync the Boost version with the CI

Change-Id: Id368c28400b9e47ccab8a5ec0cb204bd3c94bab5
diff --git a/README.md b/README.md
index e4e6c98..390c611 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,7 @@
 
 - C++20 compiler (e.g., GCC 10.x+, clang 10+)
 - CMake 3.19+
-- [Boost](https://www.boost.org/) (we're testing with `1.75`)
+- [Boost](https://www.boost.org/) (we're testing with `1.78`)
 - [`pkg-config`](https://www.freedesktop.org/wiki/Software/pkg-config/)
 - [`libnl-route`](http://www.infradead.org/~tgr/libnl/) for talking to the Linux kernel
 - [`libsystemd`](https://www.freedesktop.org/software/systemd/man/libsystemd.html) and [`systemd`](https://www.freedesktop.org/wiki/Software/systemd/) at runtime