MLECO-3962: Set specific versions for Python3.7 in requirements.txt

* For compatibility reasons, use the following versions when
  running on Python3.7:

  numpy 1.21.3
  scipy 1.7.3

Change-Id: I5213820cc64b51cfa8b4ff49a1bff030e652822d
Signed-off-by: Conor Kennedy <conor.kennedy@arm.com>
diff --git a/scripts/py/requirements.txt b/scripts/py/requirements.txt
index e75626c..500d115 100644
--- a/scripts/py/requirements.txt
+++ b/scripts/py/requirements.txt
@@ -7,11 +7,13 @@
 lxml==4.9.2
 MarkupSafe==2.0.1
 numba==0.56.4
-numpy==1.23.5
+numpy==1.21.3;python_version<="3.7"
+numpy==1.23.5;python_version>="3.8"
 Pillow==9.2.0
 pycparser==2.20
 resampy==0.3.1
-scipy==1.10.1
+scipy==1.7.3;python_version<="3.7"
+scipy==1.10.1;python_version>="3.8"
 six==1.16.0
 SoundFile==0.10.3.post1
 zipp==3.15.0