CI: convert galaxy version check to pre-commit + autodetect

scripts/galaxy_version.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python
+
+import subprocess
+import ruamel.yaml
+import os
+
+last_tag = (
+    subprocess.Popen(
+        ["git", "describe", "--tags", "--abbrev=0"], stdout=subprocess.PIPE
+    )
+    .communicate()[0]
+    .rstrip()
+    .decode("utf-8")
+    .removeprefix("v")
+    .split(".")
+)
+# Use CI provided base ref if available, else use HEAD to guess
+git_branch = os.getenv(
+    "GITHUB_BASE_REF",
+    (
+        subprocess.Popen(
+            ["git", "rev-parse", "--abbrev-ref", "HEAD"], stdout=subprocess.PIPE
+        )
+        .communicate()[0]
+        .rstrip()
+        .decode("utf-8")
+    ),
+)
+if git_branch.startswith("release"):
+    version_comp_index = 2
+else:
+    version_comp_index = 1
+
+last_tag[version_comp_index] = str(int(last_tag[version_comp_index]) + 1)
+new_tag = ".".join(last_tag)
+
+yaml = ruamel.yaml.YAML()
+yaml.indent(mapping=2, sequence=4, offset=2)
+yaml.explicit_start = True
+
+with open(
+    "galaxy.yml",
+) as galaxy_yml:
+    config = yaml.load(galaxy_yml)
+
+config["version"] = new_tag
+
+with open("galaxy.yml", "w") as galaxy_yml:
+    yaml.dump(config, galaxy_yml)