[build]: Update versions_manager.py to make versions map key unique (s…

…onic-net#7146)

py2/py3/deb packages names are case insensitive, and the versions map
key should be the same for packages whose name can have different cases.

For example, in files/build/versions/default/versions-py3, package
"click==7.1.2" is pinned; and in
files/build/versions/dockers/docker-sonic-vs/versions-py3, package
"Click==7.0" is pinned.
Without this fix, the aggregated versions-py3 file used for building
docker-sonic-vs looks like below:
...
click==7.1.2
Click==7.0
...
However, we actually want "click==7.0" to overwrite "click==7.1.2" for
docker-sonic-vs build.

scripts/versions_manager.py

@@ -22,7 +22,7 @@ class Component:
     ctype -- Component Type, such as deb, py2, etc
     dist  -- Distribution, such as stretch, buster, etc
     arch  -- Architectrue, such as amd64, arm64, etc
-    
+
     '''
     def __init__(self, versions, ctype, dist=ALL_DIST, arch=ALL_ARCH):
         self.versions = versions
@@ -44,6 +44,8 @@ def get_versions(cls, version_file):
                 offset = line.rfind('==')
                 if offset > 0:
                     package = line[:offset].strip()
+                    if 'py2' in version_file.lower() or 'py3' in version_file.lower():
+                        package = package.lower()
                     version = line[offset+2:].strip()
                     result[package] = version
         return result
@@ -86,7 +88,7 @@ def dump_to_path(self, file_path, config=False, priority=999):
         if config and self.ctype == 'deb':
             none_config_file_path = os.path.join(file_path, filename)
             self.dump_to_file(none_config_file_path, False, priority)
-            filename = VERSION_DEB_PREFERENCE 
+            filename = VERSION_DEB_PREFERENCE
         file_path = os.path.join(file_path, filename)
         self.dump_to_file(file_path, config, priority)