Add DHI ecosystem (#4388)

Adding new ecosystem for Docker Hardened Images. relates to
#4387.

Signed-off-by: Christian Dupuis <cd@docker.com>
Co-authored-by: Rex P <106129829+another-rex@users.noreply.github.com>

Author: cdupuis

osv/ecosystems/_ecosystems.py

@@ -45,6 +45,7 @@
     'CRAN': CRAN,
     'crates.io': SemverEcosystem,
     'Debian': Debian,
+    'Docker Hardened Images': SemverEcosystem,
     'Echo': DPKG,
     'GHC': GHC,
     'Go': SemverEcosystem,

osv/purl_helpers.py

@@ -48,6 +48,8 @@
         EcosystemPURL('deb', 'echo'),
     'Debian':
         EcosystemPURL('deb', 'debian'),
+    'Docker Hardened Images':
+        EcosystemPURL('dhi', None),
     # GHC
     # GIT
     # GitHub Actions