PYCBC-1678: Pin cmake version

Motivation
==========
Until we have time to investigate CMake 4.0 compatibility we should make
sure the build system will install CMake < 4.0.  Most users should not
run into this scenario as we provide wheels.

Modification
============
Pinned setup_requires CMake to >= 3.19 and < 4.0.

Change-Id: I6dcc3917ba92cbe78d421972edb18c25f17ff6e8
Reviewed-on: https://review.couchbase.org/c/couchbase-python-client/+/226432
Reviewed-by: Dimitris Christodoulou <dimitris.christodoulou@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>

Author: thejcfactor

setup.py

@@ -45,7 +45,7 @@
 # otherwise, we want to use the system executable.
 setup_requires = []
 if not CMAKE_EXE:
-    setup_requires += ["cmake"]
+    setup_requires += ["cmake>=3.19.0,<4.0.0"]
 
 print(f'Python SDK version: {PYCBC_VERSION}')