chore(liccheck): loosen urllib3 pin to >=2.6.3,<3 to track requests upgrades

CI's `liccheck` step pulled urllib3 2.7.0 (a transitive dep of requests)
which the previous strict pin `==2.6.3` rejected.  Loosening to a range
keeps the license whitelist accurate as requests upgrades urllib3 within
the 2.x line.

Author: OjusWiZard

strategy.ini

@@ -93,7 +93,7 @@ certifi: >=2019.11.28
 ; licence is MIT, but the tool does not detect it
 attrs: >=25.4.0
 ; urllib3 is MIT licensed but tool doesn't detect it
-urllib3: ==2.6.3
+urllib3: >=2.6.3,<3
 ; click is BSD-3-Clause licensed but tool doesn't detect it
 click: <8.4.0
 ; typing-extensions is PSF licensed but tool doesn't detect it