Ignore rust-toolchain.toml in CI

We set a specific default toolchain with dtolnay/rust-toolchain, we don't want
it to be overridden by the config intended for devs.

.github/actions/rust-toolchain@oldest-supported/action.yml

@@ -20,3 +20,5 @@ runs:
       with:
         targets: ${{ inputs.targets }}
         components: ${{ inputs.components}}
+    - run: rm rust-toolchain.toml
+      shell: sh

.github/actions/rust-toolchain@stable/action.yml

@@ -21,3 +21,5 @@ runs:
       with:
         targets: ${{ inputs.targets }}
         components: ${{ inputs.components }}
+    - run: rm rust-toolchain.toml
+      shell: sh

.github/workflows/main.yml

@@ -39,6 +39,7 @@ jobs:
         # Ensure that fish is available as an executable.
         PATH="$PWD/build:$PATH" build_tools/update_translations.fish --no-mo
         # Show diff output. Fail if there is any.
+        git restore --worktree rust-toolchain.toml
         git --no-pager diff --exit-code || { echo 'There are uncommitted changes after regenerating the gettext PO files. Make sure to update them via `build_tools/update_translations.fish --no-mo` after changing source files.'; exit 1; }
 
   ubuntu-32bit-static-pcre2:
@@ -87,6 +88,7 @@ jobs:
         # ASAN uses `cargo build -Zbuild-std` which requires the rust-src component
         # this is comma-separated
         components: rust-src
+    - run: rm rust-toolchain.toml
     - name: Install deps
       run: |
         sudo apt install gettext libpcre2-dev python3-pexpect tmux