workflows/release-tasks: Remove stray backslash

Reviewed By: thieta

Differential Revision: https://reviews.llvm.org/D150018

Author: tstellar

.github/workflows/release-tasks.yml

@@ -26,7 +26,7 @@ jobs:
 
       - name: Install Dependencies
         run: |
-          sudo apt-get update \
+          sudo apt-get update
           sudo apt-get install -y \
               doxygen \
               graphviz \