Add .gitlab-ci.yml

.gitlab-ci.yml

+image: ubuntu:latest
+
+stages:
+    - test
+
+test:
+    stage: test
+    script:
+        - apt-get update
+        - apt-get upgrade -y
+        - apt-get install clang build-essential -y
+        - cd build 
+        - CC=clang cmake ..
+        - make 
+        - ./tests/str_format_fuzzer_test -max_total_time=60
\ No newline at end of file