Apply MSRV to all crates (we no longer depend on ring)

README.md

@@ -52,15 +52,6 @@ Ruma currently requires Rust 1.50. In general, we will never require beta or
 nightly for crates.io releases of our crates, and we will try to avoid releasing
 crates that depend on features that were only just stabilized.
 
-There are two exceptions to this:
-
-* ruma-signatures (and hence ruma with the federation-api feature) since it
-  depends on [ring][], which is only guaranteed to work on the latest stable.
-* ruma-client depends on some I/O libraries (and also on ring, conditionally),
-  so it is also only guaranteed to work on the latest stable.
-
-[ring]: https://github.com/briansmith/ring/
-
 ## License
 
 [MIT](http://opensource.org/licenses/MIT)

xtask/src/ci.rs

@@ -39,17 +39,11 @@ impl CiTask {
 
     fn build_msrv(&self) -> xshell::Result<()> {
         // Check all crates with all features except
-        // * ruma (all-features would include the other crates)
-        // * ruma-client (due to transitive ring dependency which only supports latest stable)
-        // * ruma-signatures (for the same reason)
-        // * ruma-state-res (initially exempt from MSRV policy)
+        // * ruma-client (will be tested as part of ruma, don't want to enabled all features)
         // * xtask (no real reason to enforce an MSRV for it)
         cmd!(
             "rustup run {MSRV} cargo check --workspace --all-features
-                --exclude ruma
                 --exclude ruma-client
-                --exclude ruma-signatures
-                --exclude ruma-state-res
                 --exclude xtask"
         )
         .run()?;