fix: avoid yaml dependency for waf setup

tests/hw/libnux/with_hostcode/wscript

 import os
 from os.path import join
 import re
-import yaml
 from enum import Enum, auto
 from numbers import Integral
 
@@ -49,6 +48,7 @@ def build(bld):
         hwdb_entries = os.environ.get("SLURM_HWDB_YAML")
         fpga_id = int(re.match(r"W(?P<wafer>\d+)F(?P<fpga>\d+)",
                                slurm_licenses)["fpga"])
+        import yaml
         fpgas = yaml.full_load(hwdb_entries)["fpgas"]
         fpga = None
         for entry in fpgas:

tests/wscript

 import os
 from os.path import join
 import re
-import yaml
 from enum import Enum, auto
 
 from waflib.TaskGen import feature, after_method
@@ -56,6 +55,7 @@ def build(bld):
         hwdb_entries = os.environ.get("SLURM_HWDB_YAML")
         fpga_id = int(re.match(r"W(?P<wafer>\d+)F(?P<fpga>\d+)",
                                slurm_licenses)["fpga"])
+        import yaml
         fpgas = yaml.full_load(hwdb_entries)["fpgas"]
         fpga = None
         for entry in fpgas:

wscript

 import os
 from os.path import join
 import re
-import yaml
 from enum import Enum, auto
 
 from waflib import Logs