Update marshmallow requirement from ~=3.15.0 to ~=3.18.0 in /api

Updates the requirements on [marshmallow](https://github.com/marshmallow-code/marshmallow) to permit the latest version.
- [Release notes](https://github.com/marshmallow-code/marshmallow/releases)
- [Changelog](https://github.com/marshmallow-code/marshmallow/blob/dev/CHANGELOG.rst)
- [Commits](https://github.com/marshmallow-code/marshmallow/compare/3.15.0...3.18.0)

---
updated-dependencies:
- dependency-name: marshmallow
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/dependabot.yml

@@ -10,8 +10,6 @@ updates:
     directory: "/api"
     schedule:
       interval: "daily"
-    assignees:
-      - "H4CK3R-01"
     open-pull-requests-limit: 100
 
   # Bot
@@ -19,10 +17,6 @@ updates:
     directory: "/telegram_bot"
     schedule:
       interval: "daily"
-    assignees:
-      - "NormalParameter"
-      - "Rripped"
-      - "FlorianKellermann"
     open-pull-requests-limit: 100
   
   # Frontend
@@ -30,6 +24,4 @@ updates:
     directory: "/frontend"
     schedule:
       interval: "daily"
-    assignees:
-      - "kevinpauer"
     open-pull-requests-limit: 100

api/requirements.txt

@@ -10,7 +10,7 @@ flask-cors==3.0.10
 bcrypt==3.2.2
 pytest~=7.1.2
 pytest-cov
-marshmallow~=3.15.0
+marshmallow~=3.18.0
 faker~=13.11.0
 requests~=2.27.1
 investpy~=1.0.8