Update confidence levels prompt injection detection to reduce false positive rates (#6390)

Signed-off-by: Dorien Koelemeijer <dkoelemeijer@squareup.com>

crates/goose/src/security/scanner.rs

@@ -85,7 +85,7 @@ impl PromptInjectionScanner {
     pub fn get_threshold_from_config(&self) -> f32 {
         Config::global()
             .get_param::<f64>("SECURITY_PROMPT_THRESHOLD")
-            .unwrap_or(0.7) as f32
+            .unwrap_or(0.8) as f32
     }
 
     pub async fn analyze_tool_call_with_context(
@@ -283,7 +283,7 @@ mod tests {
         let scanner = PromptInjectionScanner::new();
         let result = scanner.analyze_text("rm -rf /").await.unwrap();
 
-        assert!(result.confidence > 0.9);
+        assert!(result.confidence >= 0.75); // High risk level = 0.75 confidence
         assert!(!result.pattern_matches.is_empty());
     }