Fix minor typos (Thanks to Shubham)

src/backends/python/pythonsession.cpp

@@ -359,13 +359,13 @@ QString PythonSession::graphicPackageErrorMessage(QString packageId) const
     if (packageId == QLatin1String("matplotlib"))
     {
         return i18n(
-            "For using integrated graphics with Matplotlib package, you need install \"matplotlib\" python package first."
+            "For using integrated graphics with Matplotlib package, you need to install \"matplotlib\" python package first."
         );
     }
     else if (packageId == QLatin1String("plotly"))
     {
         return i18n(
-            "For using integrated graphic with Plot.ly, you need install \"plotly\" python package and special Plot.ly-compatible "
+            "For using integrated graphic with Plot.ly, you need to install \"plotly\" python package and special Plot.ly-compatible "
             "\"orca\" executable. See \"Static Image Export\" article in Plot.ly documentation for details."
         );
     }

src/lib/session.cpp

@@ -367,7 +367,7 @@ void Cantor::Session::updateEnabledGraphicPackages(const QList<Cantor::GraphicPa
             {
                 KMessageBox::information(nullptr, i18n(
                     "You choose support for %1 graphic package, but the support can't be "\
-                    "activated due missing requirements, so integration for this package will be disabled. %2",
+                    "activated due to the missing requirements, so integration for this package will be disabled. %2",
                     notEnabledPackage.name(), graphicPackageErrorMessage(notEnabledPackage.id())), i18n("Cantor")
                 );