ci: Add the libpng release tags to the list of exclusions

The release tags are redundant in the CI process. It is the main branch
that is always verified.
diff --git a/.appveyor.yml b/.appveyor.yml
index e07b932..ddeb4ec 100644
--- a/.appveyor.yml
+++ b/.appveyor.yml
@@ -3,6 +3,7 @@
 branches:
   except:
     - /libpng[0-1][0-7]/
+    - /v[0-1][.][0-7][.][0-9]+/
 
 image:
   - Visual Studio 2022
diff --git a/.travis.yml b/.travis.yml
index ab3fba6..e8adbbd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,7 @@
 branches:
   except:
     - /libpng[0-1][0-7]/
+    - /v[0-1][.][0-7][.][0-9]+/
 
 language: c