python-blinker: new package (1.9.0)

Flask 3.x requires blinker for its signal system. Add python-blinker
1.9.0 as a new package.

blinker is a pure-Python package (flit-core build backend) with no
runtime dependencies.

Signed-off-by: Alexandru Ardelean <alex@shruggie.ro>

lang/python/python-blinker/test.sh

@@ -0,0 +1,37 @@
+#!/bin/sh
+
+[ "$1" = python3-blinker ] || exit 0
+
+python3 - <<EOF
+import sys
+from blinker import Signal, signal
+
+# Named signal
+data_saved = signal("data-saved")
+results = []
+cb_named = lambda sender, **kw: results.append((sender, kw))
+data_saved.connect(cb_named)
+data_saved.send("db", value=42)
+assert results == [("db", {"value": 42})], f"Unexpected: {results}"
+
+# Anonymous signal, multiple subscribers
+updated = Signal()
+log = []
+cb_a = lambda s, **kw: log.append("a")
+cb_b = lambda s, **kw: log.append("b")
+updated.connect(cb_a)
+updated.connect(cb_b)
+updated.send(None)
+assert set(log) == {"a", "b"}, f"Unexpected: {log}"
+
+# Disconnect
+def handler(sender, **kw):
+    log.append("handler")
+
+updated.connect(handler)
+updated.disconnect(handler)
+updated.send(None)
+assert "handler" not in log[2:], "handler should have been disconnected"
+
+print("python-blinker OK")
+EOF