Upgrade ci rust nightly to 2021-10-07, with fixed rust issue 89485

You can see how the issue might apply to the GroupVars
promote_plain()'s

    match self { Plain | Important => Important, _ => self }

.github/workflows/ci.yml

@@ -19,10 +19,10 @@ jobs:
         with:
           submodules: recursive
 
-      - name: Install Rust nightly-2021-08-30
+      - name: install rust nightly-2021-10-07
         uses: actions-rs/toolchain@v1
         with:
-            toolchain: nightly-2021-08-30
+            toolchain: nightly-2021-10-07
             override: true
       - uses: Swatinem/rust-cache@v1
       - run: cargo test --lib
@@ -84,10 +84,10 @@ jobs:
           S3_PREFIX='https://citeproc-rs-test-results.cormacrelf.net'
           curl -sL "$S3_PREFIX/.snapshots/branches/$GITHUB_BASE" -o ".snapshots/branches/$GITHUB_BASE"
 
-      - name: Install Rust nightly-2021-08-30
+      - name: install rust nightly-2021-10-07
         uses: actions-rs/toolchain@v1
         with:
-            toolchain: nightly-2021-08-30
+            toolchain: nightly-2021-10-07
             override: true
       - uses: Swatinem/rust-cache@v1
 

bindings/xcframework/build.sh

@@ -8,7 +8,7 @@ set -euxo pipefail
 : "${OUTNAME:=CiteprocRs}"
 # needs PR https://github.com/rust-lang/rust/pull/87699
 # install with `rustup install $TOOLCHAIN && rustup component add rust-src --toolchain $TOOLCHAIN`
-# : "${TOOLCHAIN:=nightly-2021-08-30}"
+# : "${TOOLCHAIN:=nightly-2021-10-07}"
 : "${CONFIGURATION:=test}"
 
 export IPHONEOS_DEPLOYMENT_TARGET=13.0

bindings/xcframework/rust-toolchain.toml

@@ -1,6 +1,6 @@
 [toolchain]
 # needs PR https://github.com/rust-lang/rust/pull/87699
-channel = "nightly-2021-08-30"
+channel = "nightly-2021-10-07"
 profile = "minimal"
 components = [ "rust-src" ]
 targets = [