fix: Dockerfile to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-DEBIAN12-ZLIB-6008963
- https://snyk.io/vuln/SNYK-DEBIAN12-GNUPG2-9486681
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-1549480
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-6277421
- https://snyk.io/vuln/SNYK-DEBIAN12-KRB5-8679228

Dockerfile

@@ -1,5 +1,5 @@
 # Use an official Python runtime as a parent image
-FROM python:3.14.2-slim
+FROM python:3.13.3-slim
 
 # Create a working directory
 WORKDIR /app

requirements.txt

@@ -1,5 +1,5 @@
-Flask>=2.2.5
-requests>=2.32.2
-reportlab>=3.6.13
-Faker>=18.9.0
+Flask==2.2.5
+requests==2.32.2
+reportlab==3.6.13
+Faker==18.9.0
 pillow>=10.2.0 # not directly required, pinned by Snyk to avoid a vulnerability