Bump spatialdata-plot floor to 0.3.4 and ignore pixi local state

`>=0.3.4` includes recent fixes used by the tutorials. Adds `.pixi/`
(env cache) and `pixi.lock` to `.gitignore`; pixi solves dependencies
fresh per contributor, no need to commit the lockfile.

Author: timtreis

.gitignore

@@ -15,6 +15,8 @@ dist/
 env/
 venv/
 ENV/
+.pixi/
+pixi.lock
 
 # Editors
 .idea/

pyproject.toml

@@ -16,7 +16,7 @@ authors = [{ name = "scverse" }]
 # the notebooks end-to-end.
 [project.optional-dependencies]
 exec = [
-    "spatialdata-plot>=0.3",
+    "spatialdata-plot>=0.3.4",
     "squidpy",
     "jupyter",
     "ipykernel",