Rename Rng => RngExt; bump rand_core to v0.10.0-rc-6

This prerelease of `rand_core` renamed `(Try)RngCore` => `(Try)Rng`.

Since `rand` previously defined an `Rng` trait, it now needs a new name,
and `RngExt` was the one I saw suggested in rust-random/rand_core#54.

Author: tarcieri

CHANGELOG.md

@@ -21,6 +21,7 @@ You may also find the [Upgrade Guide](https://rust-random.github.io/book/update.
 - Use `postcard` instead of `bincode` to test the serde feature (#1693)
 - Avoid excessive allocation in `IteratorRandom::sample` when `amount` is much larger than iterator size ([#1695])
 - Rename `os_rng` -> `sys_rng`, `OsRng` -> `SysRng`, `OsError` -> `SysError` ([#1697])
+- Rename `Rng` -> `RngExt` as upstream `rand_core` has renamed `RngCore` -> `Rng` ([#1717])
 
 ### Additions
 - Add fns `IndexedRandom::choose_iter`, `choose_weighted_iter` (#1632)
@@ -29,6 +30,7 @@ You may also find the [Upgrade Guide](https://rust-random.github.io/book/update.
 
 [#1695]: https://github.com/rust-random/rand/pull/1695
 [#1697]: https://github.com/rust-random/rand/pull/1697
+[#1717]: https://github.com/rust-random/rand/pull/1717
 
 ## [0.9.2] - 2025-07-20
 ### Deprecated

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "rand"
-version = "0.10.0-rc.7"
+version = "0.10.0-rc.8"
 authors = ["The Rand Project Developers", "The Rust Project Developers"]
 license = "MIT OR Apache-2.0"
 readme = "README.md"
@@ -72,11 +72,11 @@ members = [
 exclude = ["benches", "distr_test"]
 
 [dependencies]
-rand_core = { version = "0.10.0-rc-5", default-features = false }
+rand_core = { version = "0.10.0-rc-6", default-features = false }
 log = { version = "0.4.4", optional = true }
 serde = { version = "1.0.103", features = ["derive"], optional = true }
-chacha20 = { version = "0.10.0-rc.8", default-features = false, features = ["rng"], optional = true }
-getrandom = { version = "0.4.0-rc.0", optional = true }
+chacha20 = { version = "0.10.0-rc.9", default-features = false, features = ["rng"], optional = true }
+getrandom = { version = "0.4.0-rc.1", optional = true }
 
 [dev-dependencies]
 rand_pcg = { path = "rand_pcg", version = "0.10.0-rc.1" }