Update instawow.

nix/configuration/configuration.nix

@@ -283,6 +283,32 @@ in
         (disableOptimizations "zopfli")
         (disableOptimizations "nototools") # Needs to use the same version of python as the zopfli package
         (disableOptimizations "lib2geom") # Tests failing: ellipse-test, elliptical-arc-test, line-test, polynomial-test
+        (final: prev: {
+          instawow = prev.instawow.overrideAttrs (
+            finalAttrs: prevAttrs:
+            let
+              version = "7.2.1";
+            in
+            {
+              inherit version;
+
+              src = final.fetchFromGitHub {
+                owner = "layday";
+                repo = "instawow";
+                tag = "v${finalAttrs.version}";
+                hash = "sha256-5y+oJfzWwaUc3p4fzsQ4j8a6YJEsI+3Qy3gK6VPkjA4=";
+              };
+
+              propagatedBuildInputs = prevAttrs.propagatedBuildInputs ++ [ final.python3.pkgs.versioningit ];
+
+              postPatch = ''
+                # Upstream uses versioningit to set the version
+                sed -i '/^name =.*/a version = "${version}"' pyproject.toml
+                sed -i "/dynamic =/,+2d" pyproject.toml
+              '';
+            }
+          );
+        })
         (final: prev: {
           pythonPackagesExtensions = prev.pythonPackagesExtensions ++ [
             (python-final: python-prev: {