fix: backend/requirements.txt to reduce vulnerabilities

The following vulnerabilities are fixed by pinning transitive dependencies:
- https://snyk.io/vuln/SNYK-PYTHON-BLACK-6256273
- https://snyk.io/vuln/SNYK-PYTHON-FASTAPI-6228055
- https://snyk.io/vuln/SNYK-PYTHON-IDNA-6597975
- https://snyk.io/vuln/SNYK-PYTHON-REQUESTS-6928867
- https://snyk.io/vuln/SNYK-PYTHON-STARLETTE-3319937
- https://snyk.io/vuln/SNYK-PYTHON-STARLETTE-5538332

backend/requirements.txt

@@ -4,7 +4,7 @@ astroid==2.8.3
 async-generator==1.10
 attrs==21.2.0
 backports.entry-points-selectable==1.1.0
-black==21.9b0
+black==24.3.0
 bson==0.5.10
 certifi==2023.7.22
 cfgv==3.3.1
@@ -13,15 +13,15 @@ click==8.0.3
 colorama==0.4.4
 coverage==6.0.2
 distlib==0.3.3
-fastapi==0.70.0
+fastapi==0.109.1
 fastapi-pagination==0.9.1
 filelock==3.3.1
 h11==0.12.0
 httpcore==0.13.7
 httptools==0.2.0
 httpx==0.23.0
 identify==2.3.1
-idna==3.3
+idna==3.7
 iniconfig==1.1.1
 isort==5.9.3
 lazy-object-proxy==1.6.0
@@ -46,12 +46,12 @@ python-dateutil==2.8.2
 python-dotenv==0.19.1
 PyYAML==6.0
 regex==2021.10.23
-requests==2.31.0
+requests==2.32.2
 rfc3986==1.5.0
 six==1.16.0
 sniffio==1.2.0
 sortedcontainers==2.4.0
-starlette==0.16.0
+starlette==0.27.0
 toml==0.10.2
 tomli==1.2.2
 trio==0.19.0