Use lockfile when installing cargo-wix in CI

When installing a package using `cargo install`, by default it ignores
the lockfile for that package and installs the latest relevant
dependency versions. This can be overridden by using the `--locked`
flag.

Using an unlocked install is causing issues in CI, because we have our
Rust version pinned to a version that is older than the MSRV for some of
`cargo-wix`'s dependencies. Switching to a locked install means that the
dependency versions will be repeatable and so we shouldn't have issues
with Rust version mismatches.

Author: charlespierce

.github/workflows/release.yml

@@ -84,7 +84,7 @@ jobs:
         with:
           rustflags: ""
       - name: Add cargo-wix subcommand
-        run: cargo install cargo-wix
+        run: cargo install --locked cargo-wix
       - name: Compile and package installer
         run: |
           cargo wix --nocapture --package volta --output target\wix\volta-windows.msi
@@ -114,7 +114,7 @@ jobs:
           target: aarch64-pc-windows-msvc
           rustflags: ""
       - name: Add cargo-wix subcommand
-        run: cargo install cargo-wix
+        run: cargo install --locked cargo-wix
       - name: Compile and package installer
         run: |
           cargo wix --nocapture --package volta --target aarch64-pc-windows-msvc --output target\wix\volta-windows-arm.msi