Update build-book.yml

Author: gcarcassi

.github/workflows/build-book.yml

@@ -31,7 +31,7 @@ jobs:
           cd book
           curl -L https://raw.githubusercontent.com/aslushnikov/latex-online/master/util/latexonline > laton && chmod 755 laton
           ls -l
-          laton book.tex
+          ./laton book.tex
           ls -l
           # Add possible changes
           cd ../autogen