[packit] 0.20.2 upstream release

Upstream tag: 0.20.2
Upstream commit: 4486a88c

If you need to do any change in this pull request, you need to locally fetch the source branch of it and push it (with a fix) to your fork (as it is not possible to push to the branch created in the Packit’s fork):
```
git fetch https://src.fedoraproject.org/forks/packit/rpms/python-specfile.git refs/heads/*:refs/remotes/packit/*
git checkout packit/0.20.2-epel8-update-propose_downstream
```

plans/git_reference.py

@@ -5,10 +5,25 @@ from pathlib import Path
 
 import fmf
 
+# Set discover of specfile tests to a fixed commit
 tree_root = Path.cwd().absolute()
-node = fmf.Tree(tree_root).find("/plans")
-with node as data:
+tree = fmf.Tree(tree_root)
+main_node = tree.find("/plans")
+with main_node as data:
     data["discover"]["url"] = "https://github.com/packit/specfile.git"
     data["discover"]["ref"] = (
         subprocess.check_output(["git", "rev-parse", "HEAD"]).decode().strip()
     )
+
+
+# Set discover of packit integration tests to the current main
+packit_node = tree.find("/plans/packit-integration")
+with packit_node as data:
+    data["discover"]["ref"] = (
+        subprocess.check_output(
+            ["git", "ls-remote", "https://github.com/packit/packit", "main"]
+        )
+        .decode()
+        .strip()
+        .split()[0]
+    )

plans/main.fmf

@@ -1,6 +1,6 @@
 discover:
     how: fmf
     url: https://github.com/packit/specfile.git
-    ref: e121363bba69e8fcc49eac8df4d6ef60ef1acf69
+    ref: 4486a88c56fdfdea0c8b1e16f32a76056e9faba3
 execute:
     how: tmt

plans/packit-integration.fmf

@@ -0,0 +1,27 @@
+discover:
+    how: fmf
+    url: https://github.com/packit/packit
+    filter: tier:0 | tier:1
+    ref: 4b998555d18e3e7abfb7a521b3b65a34de02dc76
+prepare:
+  - how: install
+    copr: packit/packit-dev
+  - how: shell
+    script: dnf -y config-manager --save --setopt="*:packit:packit-dev.priority=5"
+adjust:
+  - when: how == integration
+    because: provide latest python-specfile rpm when running locally
+    prepare+:
+      - name: python3-specfile rpm
+        how: install
+        directory: noarch/
+  - when: distro == rhel-9 or distro == centos-9 or distro == centos-stream-9
+    because: 'flexmock and deepdiff are not in EPEL 9: https://bugzilla.redhat.com/show_bug.cgi?id=2120251'
+    prepare+:
+      - how: install
+        package: python3-pip
+      - how: shell
+        script: pip3 install flexmock deepdiff
+  - when: distro == rhel-8 or distro == centos-8 or distro == centos-stream-8
+    because: packit doesn't support EL 8
+    enabled: false