Update Apache RAT version from 0.17 to 0.18

.github/workflows/rat.yaml

diff --git a/.github/workflows/rat.yaml b/.github/workflows/rat.yaml
index ffe464b..23ed6e9 100644
--- a/.github/workflows/rat.yaml
+++ b/.github/workflows/rat.yaml
@@ -42,12 +42,12 @@
 
       - name: Download Apache RAT
         run: |
-          curl -L -O https://downloads.apache.org/creadur/apache-rat-0.17/apache-rat-0.17-bin.tar.gz
-          tar -xzf apache-rat-0.17-bin.tar.gz
+          curl -L -O https://downloads.apache.org/creadur/apache-rat-0.18/apache-rat-0.18-bin.tar.gz
+          tar -xzf apache-rat-0.18-bin.tar.gz
 
       - name: Run RAT
         run: |
-          java -jar apache-rat-0.17/apache-rat-0.17.jar -d . -E .rat-excludes > rat-report.txt
+          java -jar apache-rat-0.18/apache-rat-0.18.jar -d . -E .rat-excludes > rat-report.txt
           cat rat-report.txt
           # Fail if unapproved licenses are found
           grep -qe '^\s*Unapproved:\s*0\s*A count of unapproved licenses.$' rat-report.txt && exit 0 || exit 1