ci: add more ARM build configurations to CI and release workflows

... it turns out that rustembedded/cross:armv7-unknown-linux-musleabi
doesn't exist. And looking more closely, it looks like the Cross project
has decided to shake things up and publish images to ghcr instead. So we
migrate everything over to that.

tests/feature.rs

@@ -972,7 +972,7 @@ rgtest!(f1404_nothing_searched_warning, |dir: Dir, mut cmd: TestCommand| {
     cmd.assert_err();
 
     // Test that we actually get an error message that we expect.
-    let output = cmd.cmd().output().unwrap();
+    let output = cmd.raw_output();
     let stderr = String::from_utf8_lossy(&output.stderr);
     let expected = "\
         No files were searched, which means ripgrep probably applied \
@@ -995,7 +995,7 @@ rgtest!(f1404_nothing_searched_ignored, |dir: Dir, mut cmd: TestCommand| {
 
     // But since --no-messages is given, there should not be any error message
     // printed.
-    let output = cmd.cmd().output().unwrap();
+    let output = cmd.raw_output();
     let stderr = String::from_utf8_lossy(&output.stderr);
     let expected = "";
     eqnice!(expected, stderr);