fix: 7.1/apache/Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN10-DPKG-2847944
- https://snyk.io/vuln/SNYK-DEBIAN10-LIBXML2-2413976
- https://snyk.io/vuln/SNYK-DEBIAN10-OPENSSL-2807585
- https://snyk.io/vuln/SNYK-DEBIAN10-OPENSSL-2933515
- https://snyk.io/vuln/SNYK-DEBIAN10-OPENSSL-2933515

7.1/apache/Dockerfile

@@ -1,4 +1,4 @@
-FROM php:7.3.33-fpm-buster
+FROM php:7.4-fpm-buster
 MAINTAINER louisbl <louisbl@beltramo.me>
 
 RUN apt-get update && apt-get install -y \