Bump version to 3.1.2

Author: robbievanleeuwen

.github/release-drafter.yml

@@ -53,7 +53,7 @@ exclude-contributors:
 
 # Custom text at start of release
 header: |
-  Minor release for Zenodo archival.
+  This release makes `numba` an optional dependency, adds strict `mypy` type checking and modifies the application of the Lagrangian Multipler method.
 
 template: |
   ## What's Changed

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "sectionproperties"
-version = "3.1.1"
+version = "3.1.2"
 description = "A python package for the analysis of arbitrary cross-sections using the finite element method."
 license = "MIT"
 authors = [