Bump version of pub_semver to 1.4.4 (#2367)

diff --git a/pubspec.yaml b/pubspec.yaml
index 44b3e26..99477c8 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -22,7 +22,7 @@
   path: ^1.2.0
   pedantic: ^1.9.0
   pool: ^1.0.0
-  pub_semver: ^1.4.0
+  pub_semver: ^1.4.4
   shelf: ^0.7.0
   source_span: ^1.4.0
   stack_trace: ^1.0.0