fix: fix postcss flexbox warnings (#5859)

Author: MarcusNotheis

packages/main/src/components/ActionSheet/ActionSheet.module.css

@@ -8,7 +8,7 @@
 }
 
 .actionSheet [ui5-button]:not([data-cancel-btn])::part(button) {
-  justify-content: start;
+  justify-content: flex-start;
 }
 
 .actionSheet::part(header) {

packages/main/src/components/FilterGroupItem/FilterGroupItem.module.css

@@ -14,7 +14,7 @@
 .innerFilterItemContainer {
   display: flex;
   flex-direction: column;
-  justify-content: start;
+  justify-content: flex-start;
 
   > :last-child {
     width: 100%;

packages/main/src/components/SelectDialog/SelectDialog.module.css

@@ -54,7 +54,7 @@
 .footer {
   display: flex;
   align-items: center;
-  justify-content: end;
+  justify-content: flex-end;
   width: 100%;
   box-sizing: border-box;
 

packages/main/src/components/Toolbar/Toolbar.module.css

@@ -115,7 +115,7 @@
 
   > [ui5-button]::part(button),
   > [ui5-toggle-button]::part(button) {
-    justify-content: start;
+    justify-content: flex-start;
   }
 
   > [ui5-button][icon-only]::part(button),