Fix all instances

Author: HyukjinKwon

.github/workflows/master.yml

@@ -105,7 +105,7 @@ jobs:
         java-version: '11'
     - name: install R
       run: |
-        echo 'deb https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/' | sudo tee -a /etc/apt/sources.list
+        echo 'deb https://cloud.r-project.org/bin/linux/ubuntu/bionic-cran35/' | sudo tee -a /etc/apt/sources.list
         curl -sL "https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xE298A3A825C0D65DFD57CBB651716619E084DAB9" | sudo apt-key add
         sudo apt-get update
         sudo apt-get install -y r-base r-base-dev libcurl4-openssl-dev

dev/create-release/spark-rm/Dockerfile

@@ -43,7 +43,7 @@ ARG GEM_PKGS="jekyll:4.0.0 jekyll-redirect-from:0.16.0 rouge:3.15.0"
 # This is all in a single "RUN" command so that if anything changes, "apt update" is run to fetch
 # the most current package versions (instead of potentially using old versions cached by docker).
 RUN apt-get clean && apt-get update && $APT_INSTALL gnupg ca-certificates && \
-  echo 'deb https://cloud.r-project.org/bin/linux/ubuntu bionic-cran35/' >> /etc/apt/sources.list && \
+  echo 'deb https://cloud.r-project.org/bin/linux/ubuntu/bionic-cran35/' >> /etc/apt/sources.list && \
   gpg --keyserver keyserver.ubuntu.com --recv-key E298A3A825C0D65DFD57CBB651716619E084DAB9 && \
   gpg -a --export E084DAB9 | apt-key add - && \
   apt-get clean && \