Update CI image to root:6.30.02-alma9

.gitlab-ci.yml

 # Taken from https://hub.docker.com/r/rootproject/root
-image: rootproject/root:6.30.02-conda
+image: rootproject/root:6.30.02-alma9
 
 stages:
   - run
@@ -17,8 +17,9 @@ cache:
 before_script:
   - set +e
   - export PATH=${HOME}/.local/bin/:$PATH
+  - dnf install xrootd-client xrootd-server python3-xrootd -y
   - pip install --user .
-  - python -c 'import quickstats as q; print(q.__version__)'
+  - python3 -c 'import quickstats as q; print(q.__version__)'
 
 fit_bbyy:
   stage: run
@@ -63,6 +64,7 @@ compare_bbyy:
    file3: limits_summary.json
    file4: kl.json
  script:
+    - dnf install diffutils -y
     - sed -i '/total_time/d' .ci/bbyy/$file1 output_ci_bbyy/$file1
     - diff .ci/bbyy/$file1 output_ci_bbyy/$file1
     - if [[ $? -ne 0 ]]; then echo "$file1 not equal"; exit 1; else echo "$file1 equal"; fi;
@@ -84,6 +86,7 @@ compare_bbtautau:
    file3: limits_summary.json
    file4: kl.json
  script:
+    - dnf install diffutils -y
     - sed -i '/total_time/d' .ci/bbtautau/$file1 output_ci_bbtautau/$file1
     - diff .ci/bbtautau/$file1 output_ci_bbtautau/$file1
     - if [[ $? -ne 0 ]]; then echo "$file1 not equal"; exit 1; else echo "$file1 equal"; fi;