v8.0 module release (#22975)

https://mattermost.atlassian.net/browse/MM-52079

```release-note
We upgrade the module version to 8.0. The new module path is github.com/mattermost-server/server/v8.
```


Co-authored-by: Doug Lauder <wiggin77@warpmail.net>

server/model/version_test.go

@@ -0,0 +1,64 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestSplitVersion(t *testing.T) {
+	major1, minor1, patch1 := SplitVersion("junk")
+	require.EqualValues(t, 0, major1)
+	require.EqualValues(t, 0, minor1)
+	require.EqualValues(t, 0, patch1)
+
+	major2, minor2, patch2 := SplitVersion("1.2.3")
+	require.EqualValues(t, 1, major2)
+	require.EqualValues(t, 2, minor2)
+	require.EqualValues(t, 3, patch2)
+
+	major3, minor3, patch3 := SplitVersion("1.2")
+	require.EqualValues(t, 1, major3)
+	require.EqualValues(t, 2, minor3)
+	require.EqualValues(t, 0, patch3)
+
+	major4, minor4, patch4 := SplitVersion("1")
+	require.EqualValues(t, 1, major4)
+	require.EqualValues(t, 0, minor4)
+	require.EqualValues(t, 0, patch4)
+
+	major5, minor5, patch5 := SplitVersion("1.2.3.junkgoeswhere")
+	require.EqualValues(t, 1, major5)
+	require.EqualValues(t, 2, minor5)
+	require.EqualValues(t, 3, patch5)
+}
+
+func TestGetPreviousVersion(t *testing.T) {
+	require.Equal(t, "1.2.0", GetPreviousVersion("1.3.0"))
+	require.Equal(t, "1.1.0", GetPreviousVersion("1.2.1"))
+	require.Equal(t, "1.0.0", GetPreviousVersion("1.1.0"))
+	require.Equal(t, "0.7.0", GetPreviousVersion("1.0.0"))
+	require.Equal(t, "0.6.0", GetPreviousVersion("0.7.1"))
+	require.Equal(t, "", GetPreviousVersion("0.5.0"))
+}
+
+func TestIsCurrentVersion(t *testing.T) {
+	major, minor, patch := SplitVersion(CurrentVersion)
+
+	require.True(t, IsCurrentVersion(CurrentVersion))
+	require.True(t, IsCurrentVersion(fmt.Sprintf("%v.%v.%v", major, minor, patch+100)))
+	require.False(t, IsCurrentVersion(fmt.Sprintf("%v.%v.%v", major, minor+1, patch)))
+	require.False(t, IsCurrentVersion(fmt.Sprintf("%v.%v.%v", major+1, minor, patch)))
+}
+
+func TestIsPreviousVersionsSupported(t *testing.T) {
+	require.True(t, IsPreviousVersionsSupported(versionsWithoutHotFixes[0]))
+	require.True(t, IsPreviousVersionsSupported(versionsWithoutHotFixes[1]))
+	require.True(t, IsPreviousVersionsSupported(versionsWithoutHotFixes[2]))
+	require.False(t, IsPreviousVersionsSupported(versionsWithoutHotFixes[4]))
+	require.False(t, IsPreviousVersionsSupported(versionsWithoutHotFixes[5]))
+}