Fixed typo

Author: StuartWheater

.circleci/config.yml

@@ -23,7 +23,7 @@ jobs:
       - run:
           command: |
               sudo apt-get install -y libxml2-dev libcurl4-openssl-dev libssl-dev libgsl-dev libgit2-dev
-              sudo apt-get install -y libharfbuzz-dev libfribidi-dev libmagick++-dev libudunit2-dev
+              sudo apt-get install -y libharfbuzz-dev libfribidi-dev libmagick++-dev libudunits2-dev
       - run:
           command: |
               sudo Rscript -e "install.packages('devtools', dependencies=TRUE)"