build: Bump MSRV to 1.89.0

This is required to support exclusive locking on files which is needed
for safe test ID generation when using nextest (since it runs each test
as a separate process.)

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

.github/workflows/release.yaml

@@ -45,7 +45,7 @@ jobs:
           target: ${{ matrix.platform.target }}
           args: ${{ matrix.platform.args  }}
           strip: true
-          toolchain: "1.88.0"
+          toolchain: "1.89.0"
       - name: Copy Release Binaries
         if: github.event_name == 'create' && github.event.ref_type == 'tag'
         shell: bash