maint: Update Nix

(cherry picked from commit 203f5d519369235097fef2bdaefa6b3d0f5e963b)

rust/nix-flake/src/lib.rs

@@ -0,0 +1,26 @@
+use anyhow::Result;
+use nix_c_raw as raw;
+use nix_util::context::{self, Context};
+
+pub struct FlakeSettings {
+    pub(crate) ptr: *mut raw::flake_settings,
+}
+impl Drop for FlakeSettings {
+    fn drop(&mut self) {
+        unsafe {
+            raw::flake_settings_free(self.ptr);
+        }
+    }
+}
+impl FlakeSettings {
+    pub fn new() -> Result<Self> {
+        let mut ctx = Context::new();
+        let s = unsafe { context::check_call!(raw::flake_settings_new(&mut ctx)) }?;
+        Ok(FlakeSettings { ptr: s })
+    }
+    pub fn init_globally(&mut self) -> Result<()> {
+        let mut ctx = Context::new();
+        unsafe { context::check_call!(raw::flake_init_global(&mut ctx, self.ptr)) }?;
+        Ok(())
+    }
+}