test: Reduce unit test requirements

Author: epage

src/value.rs

@@ -891,7 +891,12 @@ mod tests {
     #[cfg(feature = "toml")]
     fn test_i64() {
         let c = Config::builder()
-            .add_source(File::new("tests/types/i64.toml", FileFormat::Toml))
+            .add_source(File::from_str(
+                "
+value = 120
+",
+                FileFormat::Toml,
+            ))
             .build()
             .unwrap();