[xy] Install pacman R package in dockerfile. (mage-ai#1252)

Author: wangxiaoyou1993

Diff for: Dockerfile

@@ -9,6 +9,7 @@ RUN ${PIP} install "mage-ai[all]"
 
 # Install NFS dependencies
 RUN apt -y update && apt -y install nfs-common
+RUN R -e "install.packages('pacman', repos='http://cran.us.r-project.org')"
 
 # Install R
 RUN apt install -y r-base

Diff for: dev.Dockerfile

@@ -12,6 +12,7 @@ RUN apt install nodejs
 
 # Install R
 RUN apt install -y r-base
+RUN R -e "install.packages('pacman', repos='http://cran.us.r-project.org')"
 
 # Install Python dependencies
 COPY requirements.txt requirements.txt