ci: fix typo

.github/workflows/book.yml

@@ -9,7 +9,7 @@ jobs:
   build:
     name: Build the book
     runs-on: ubuntu-latest
-  setep:
+  steps:
     - name: Prepare
       run: sudo apt install po4a python3-polib libxml2 xsltproc docbook-xml docbook-xsl tidy fop gettext subversion
     - name: Checkout