Update library/Cargo.toml in weekly job

Before the workspace split, the library was covered by the weekly `cargo
update` cron job. Now that the library has its own workspace, it doesn't
get these updates.

Add `library/Cargo.toml` to the job so updates happen again.

.github/workflows/dependencies.yml

@@ -64,6 +64,10 @@ jobs:
       - name: cargo update
         # Remove first line that always just says "Updating crates.io index"
         run: cargo update 2>&1 | sed '/crates.io index/d' | tee -a cargo_update.log
+      - name: cargo update library
+        run: |
+          echo -e "\nlibrary dependencies:" >> cargo_update.log
+          cargo update --manifest-path library/Cargo.toml 2>&1 | sed '/crates.io index/d' | tee -a cargo_update.log
       - name: cargo update rustbook
         run: |
           echo -e "\nrustbook dependencies:" >> cargo_update.log
@@ -74,6 +78,7 @@ jobs:
           name: Cargo-lock
           path: |
             Cargo.lock
+            library/Cargo.lock
             src/tools/rustbook/Cargo.lock
           retention-days: 1
       - name: upload cargo-update log artifact for use in PR
@@ -119,7 +124,7 @@ jobs:
           git config user.name github-actions
           git config user.email github-actions@github.com
           git switch --force-create cargo_update
-          git add ./Cargo.lock ./src/tools/rustbook/Cargo.lock
+          git add ./Cargo.lock ./library/Cargo.lock ./src/tools/rustbook/Cargo.lock
           git commit --no-verify --file=commit.txt
 
       - name: push