fix: pin mypy to 1.15

check if we can unpin once this is merged:
dry-python/returns#2149

Author: rarescosma

pyproject.toml

@@ -50,7 +50,7 @@ dev-dependencies = [
   "bumpversion>=0.6",
   "coverage[toml]>=7.6.4",
   "isort>=5.13",
-  "mypy>=1.12",
+  "mypy==1.15",
   "ptyprocess>=0.7",
   "pycln>=2.4",
   "pylint>=3.3",