Try to add Dockerfile to root

.drone.yml

@@ -11,7 +11,7 @@ steps:
   - name: image-app
     image: plugins/docker
     settings:
-      dockerfile: ./Source/Dockerfile
+      dockerfile: ./Dockerfile
       context: Source/
       registry: hub.codefirst.iut.uca.fr
       repo: hub.codefirst.iut.uca.fr/dorian.hodin/sae4.01_formulaire

Dockerfile

@@ -1,7 +1,7 @@
 FROM php:8.1-apache
 RUN apt-get update && apt-get install -y git zip
-COPY . /var/www/html
-WORKDIR /var/www/html/Config
+COPY ./Source /var/www/html
+WORKDIR /var/www/html/Source/Config
 RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer
 RUN composer update && composer install
 RUN a2enmod rewrite