Use MPL as license specifier for plugins only requiring GStreamer < 1.20

And use MPL-2.0 for all that require GStreamer 1.20 or newer. The new
string is only allowed in 1.20 or newer and using it in older versions
causes failure to load the plugin.

All affected plugins are of course still MPL-2.0 licensed.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/issues/374

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1235>

docs/plugins/gst_plugins_cache.json

@@ -5546,7 +5546,7 @@
             }
         },
         "filename": "gstrsonvif",
-        "license": "MPL",
+        "license": "MPL-2.0",
         "other-types": {},
         "package": "gst-plugin-onvif",
         "source": "gst-plugin-onvif",
@@ -5811,7 +5811,7 @@
             }
         },
         "filename": "gstrsrtp",
-        "license": "MPL",
+        "license": "MPL-2.0",
         "other-types": {},
         "package": "gst-plugin-rtp",
         "source": "gst-plugin-rtp",
@@ -8548,7 +8548,7 @@
             }
         },
         "filename": "gsttogglerecord",
-        "license": "MPL-2.0",
+        "license": "MPL",
         "other-types": {},
         "package": "gst-plugin-togglerecord",
         "source": "gst-plugin-togglerecord",

net/onvif/src/lib.rs

@@ -130,7 +130,7 @@ gst::plugin_define!(
     env!("CARGO_PKG_DESCRIPTION"),
     plugin_init,
     concat!(env!("CARGO_PKG_VERSION"), "-", env!("COMMIT_ID")),
-    "MPL",
+    "MPL-2.0",
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_REPOSITORY"),

net/rtp/src/lib.rs

@@ -31,7 +31,7 @@ gst::plugin_define!(
     env!("CARGO_PKG_DESCRIPTION"),
     plugin_init,
     concat!(env!("CARGO_PKG_VERSION"), "-", env!("COMMIT_ID")),
-    "MPL",
+    "MPL-2.0",
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_REPOSITORY"),

utils/togglerecord/src/lib.rs

@@ -26,7 +26,7 @@ gst::plugin_define!(
     plugin_init,
     concat!(env!("CARGO_PKG_VERSION"), "-", env!("COMMIT_ID")),
     // FIXME: MPL-2.0 is only allowed since 1.18.3 (as unknown) and 1.20 (as known)
-    "MPL-2.0",
+    "MPL",
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_NAME"),
     env!("CARGO_PKG_REPOSITORY"),