ci: fix YAML syntax error

.github/workflows/book.yml

@@ -20,11 +20,11 @@ jobs:
       run: svn co http://svn.linuxfromscratch.org/lfs/trunk/BOOK $HOME/lfs-en
     - name: Update po Files
       run: make MLANG=zh_CN pofiles LFS_EN=$HOME/lfs-en
-    - name: Generate Translated XML Files:
+    - name: Generate Translated XML Files
       run: make MLANG=zh_CN booksrc MLANG=zh_CN
-    - name: Generate Translated Book (sysv):
+    - name: Generate Translated Book (sysv)
       run: make MLANG=zh_CN REV=sysv BASEDIR=$HOME/lfs-sysv html nochunks pdf
-    - name: Generate Translated Book (systemd):
+    - name: Generate Translated Book (systemd)
       run: make MLANG=zh_CN REV=systemd BASRDIR=$HOME/lfs-systemd html nochunks pdf
     - name: Upload Artifacts
       uses: actions/upload-artifact@v2