Limit py-consul version depending on python version (#3336)

Latest release is incompatible with python < 3.9

.github/workflows/install_deps.py

@@ -27,12 +27,17 @@ def install_requirements(what):
     requirements += ['psycopg[binary]'] if sys.version_info >= (3, 8, 0) and\
         (sys.platform != 'darwin' or what == 'etcd3') else ['psycopg2-binary==2.9.9' 
                                                             if sys.platform == 'darwin' else 'psycopg2-binary']
+
+    from pip._vendor.distlib.markers import evaluator, DEFAULT_CONTEXT
+    from pip._vendor.distlib.util import parse_requirement
+
     for r in read('requirements.txt').split('\n'):
-        r = r.strip()
-        if r != '':
-            extras = {e for e, v in EXTRAS_REQUIRE.items() if v and any(r.startswith(x) for x in v)}
-            if not extras or what == 'all' or what in extras:
-                requirements.append(r)
+        r = parse_requirement(r)
+        if not r or r.marker and not evaluator.evaluate(r.marker, DEFAULT_CONTEXT):
+            continue
+        extras = {e for e, v in EXTRAS_REQUIRE.items() if v and any(r.requirement.startswith(x) for x in v)}
+        if not extras or what == 'all' or what in extras:
+            requirements.append(r.requirement)
 
     return subprocess.call([sys.executable, '-m', 'pip', 'install'] + requirements)