fix(deps): silence polars explode() empty_as_null deprecation warnings

pytest emitted 113 DeprecationWarnings, all from the same source: polars
2.0 changes explode()'s default handling of empty lists from "explode to
null" to "drop the row". Every explode() call site in this repo already
follows the explode with drop_nulls() (or otherwise excludes empty
lists), so the new behavior is what we always wanted — pass
empty_as_null=False explicitly rather than suppressing the warning.

Bump the polars floor from >=1.0 to >=1.43, since the empty_as_null
kwarg doesn't exist before ~1.35.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012dE2r7cNo9Lbthh1JUW1NF

pyproject.toml

@@ -6,7 +6,7 @@ readme = "README.md"
 requires-python = ">=3.12"
 dependencies = [
     "numpy>=1.26,<3",
-    "polars>=1.0,<2",
+    "polars>=1.43,<2",
     "pyarrow>=16,<26",
     "tqdm>=4.60,<5",
     "typer>=0.12,<1",
@@ -43,11 +43,11 @@ wandb = [
 convert = [
     "uproot>=5.3,<6",
     "awkward>=2.6,<3",
-    "polars>=1.0,<2",
+    "polars>=1.43,<2",
 ]
 analysis = [
     "matplotlib>=3.8,<4",
-    "polars>=1.0,<2",
+    "polars>=1.43,<2",
     "ipykernel>=7.3.0",
     # KIT matplotlib theme, published from git.larsbogner.de. Only the local
     # `giant analyze render` step imports it; compute workers never do.